The Governor of the Mexican state that borders Arizona is collaborating with one of the world's most powerful drug traffickers, creating a haven for smugglers who transport vast quantities of narcotics into the United States, according to American officials and intelligence.

Officials said this conclusion was based on a wealth of evidence, including ''highly reliable'' informers' reports that the Governor, Manlio Fabio Beltrones Rivera, took part in meetings in which leading traffickers paid high-level politicians who were protecting their operations.

According to the accounts, Raul Salinas de Gortari, the brother of the former President, received suitcases full of cash and was responsible for distributing the money to those attending.

Present and former officials said the evidence of Mr. Beltrones's role was so detailed and compelling that the United States had included his name on a confidential document provided to the transition team of President Ernesto Zedillo listing more than a dozen officials suspected of corruption. Another Mexican Governor, Jorge Carrillo Olea, was also included on the American blacklist because of reported entanglements with major drug dealers.

While Mr. Zedillo did not name either man to a federal post, both continue to wield considerable power in their states and nationally through their prominence in Mexico's governing party. Both seem to enjoy a tacit immunity from concerted criminal investigation in Mexico and the United States.

Although Mexican governors are popularly elected, presidents have the power in practice to force their removal.

Mr. Beltrones, in an interview, denied any links to drug traffickers and disputed American law enforcement officials' assertions that Amado Carrillo Fuentes, one of Mexico's most wanted drug kingpins, was operating with impunity in his state, Sonora. In addition, Mr. Carrillo Olea, who presides over Morelos, the state just south of Mexico City, disputed charges that he had cooperated with traffickers.

In a four-month investigation that draws on intelligence documents and interviews in the United States and Mexico, The New York Times examined how both Governments handled the allegations against the two Governors.

The result is a picture of official frustration on both sides of the border and, several officials asserted, a case study of why traffickers' political patrons often go unpunished.

Despite the recent disclosures about official corruption, American officials say the Clinton Administration is planning to certify later this month that Mexico is cooperating with anti-drug efforts.

Senior Administration officials say that decision reflects a belief that Mexico's leadership is doing all it can against staggering odds.

But many law enforcement officials say it also shows that the Clinton Administration considers the narcotics fight less important than fostering commerce with this country's third-largest trading partner. Thus, these officials assert, intelligence reports suggesting corruption among Mexican politicians like Mr. Beltrones receive little attention in Washington. Similarly, agents working in Mexico feel they will get little support if they scrutinize the activities of powerful Mexican officials.

President Clinton praised Mexico last week for arresting the head of its anti-narcotics program on drug charges, citing the act as evidence that corruption, even ''at the highest levels,'' was not being tolerated.

Privately, however, American officials acknowledge that Mexican traffickers' political patrons are seldom the targets of law enforcement officials in either country, even though they play an important role in the drug trade.

In a previously undisclosed draft analysis, intelligence officials assert that Mexican traffickers take in as much as $10 billion annually, then spend as much as 60 percent of that money on bribes for officials at all levels. Officials say much of the derogatory information about Mr. Beltrones and Mr. Carrillo Olea, a former director of Mexico's anti-narcotics program, has been gathered through intelligence reports from informers, ranging from inside accounts to raw gossip. Their volume, specificity and persistence over time have persuaded many American officials that the allegations against the Governors are well founded.

But officials said such material was of little use to prosecutors, who build their cases around witnesses willing to testify in American courts.

In addition, American law enforcement officials acknowledge a reluctance to invest time and money in pursuing corrupt foreign officials.

The Protection Racket
Word May Be Out, But Proof Is Lacking

''In Mexico,'' said one American prosecutor in a border state, ''political protection is difficult to prove. If we could prove it, we'd have them all under indictment. There's a big difference between knowing something and proving it in a court of law.

''You have extremely reliable intelligence sources, but unless you can prove it, why burn your sources? You'd have their body parts spread all over Sonora.''

Mr. Beltrones, for his part, says the reports collected by American intelligence and drug agents were fabricated by political rivals. ''This sounds like a novel, filled with horror and error,'' he said. ''At what time of the day do I govern, if I'm spending my time on all these crimes?''

Wilburn Sears, a veteran agent with bulging forearms and a walrus mustache, took charge of the Drug Enforcement Administration's five-person office in Hermosillo, the capital of Sonora, in 1991. He soon came to the realization that the state was overrun by traffickers.

Mexico's second-largest state in size, Sonora was ideal terrain for smugglers, a sprawling region of cattle ranches and desert landing strips etched with rail lines and lonely roads leading north to more than 300 miles of remote border.

Vast quantities of marijuana were pouring up the highways. Passenger cars were ferrying methamphetamines over the line into Arizona. And the traffickers were traveling in and out of Hermosillo and other Sonoran cities in long convoys or in private jets, under the noses of state and federal police officers.

''The feds were protecting the airports,'' Mr. Sears said in a recent interview. ''They were doing everything out there except kick-starting the narcos' airplanes.''

It was in those years that Mr. Carrillo Fuentes began the ascent that would make him one of Mexico's shrewdest and most influential drug smugglers. The nephew of one of the country's narcotics pioneers, he had been building his organization in the late 1980's, wooing marijuana farmers to the south in Sinaloa, the heroin clans of Durango and especially the cocaine barons of Cali, Colombia. Most of all, he had cultivated the skills of Mexican narcotics diplomacy and knew what it took to buy protection from powerful politicians.

In a lengthy 1994 study, the Drug Enforcement Administration's analysts in El Paso, Texas, painted a detailed picture of how Mr. Carrillo Fuentes cultivated Mexican police officials and political leaders, including Mr. Beltrones and Mr. Carrillo Olea. According to the classified analysis, based on field reports from more than a dozen American agencies, the trafficker has ''purchased influence at various key levels in the Mexican Government,'' giving him ''powerful connections'' that insure safe passage of his drug loads through Mexico to the United States.

A Political Operator
Showing Potential For a Rapid Rise

In the early 1990's, Mr. Carrillo Fuentes was moving to make Hermosillo a strategic staging area, American officials said. He was living in a pink stucco mansion down the street from the American consul's residence in a palm-fringed neighborhood. He had begun construction of a much more extravagant, onion-domed house -- locals called it a Thousand and One Nights -- a few blocks north. And among other properties he or his associates had acquired was a communications center across town.

In August 1991 Mr. Beltrones was elected, and in October he moved into the colonial-style governor's palace in Hermosillo. He was a rising star in the Institutional Revolutionary Party, one of a handful of ambitious 40-something leaders sometimes called the ''babysaurs,'' to distinguish them from the older ''dinosaurs'' who have long ruled the party. During his early career, Mr. Beltrones had been the understudy to Fernando Gutierrez Barrios, Mr. Salinas's Interior Minister and one of the pioneers of Mexico's secret police. Some have seen Mr. Beltrones as a possible presidential candidate.

But about the time that he took the oath of office, United States officials began picking up reports from confidential informers documenting his ties to Mr. Carrillo Fuentes. In an interview, Mr. Beltrones raised his voice when reporters described D.E.A. reports alleging that he had accepted payments from Mr. Carrillo Fuentes.

''These reports are incredible in every sense, filled with fantasy and lies,'' Mr. Beltrones said. The D.E.A., he added, ''is completely out of focus.''

As evidence of his hostility to drug trafficking, Mr. Beltrones asserted that he had virtually driven Mr. Carrillo Fuentes from Hermosillo.

A high-ranking Mexican official said that Mr. Beltrones learned of Mr. Carrillo Fuentes's residences in Hermosillo shortly after he took office. Months later, the official said, Mr. Beltrones ordered aides to videotape Mr. Carrillo Fuentes's arrival at the local airport in a Lear jet, and his travels about the state capital in a convoy guarded by police vehicles. The Governor delivered the tape to President Carlos Salinas de Gortari, the official added, and federal authorities later confiscated four of Mr. Carrillo Fuentes's properties, including the onion-domed mansion.

''How would the D.E.A. explain that I'm the one who took away this man's houses?'' Mr. Beltrones asked.

American officials and reports acknowledge that four of Mr. Carrillo Fuentes's Hermosillo houses were seized. But they said his organization continued to use at least eight other properties, including the communications center. The officials maintain that Sonora remains one of Mr. Carrillo Fuentes's most important operating bases.

In the early 1990's, Mr. Carrillo Fuentes set out to increase his air smuggling operations, and for that he needed help at the highest levels of the federal bureaucracy. Under Mexican law the federal government enforces the drug statutes.

At the time, Mexican authorities were working with their American counterparts to perfect a radar network that tracked aircraft flying north from Colombia. The system allowed controllers to follow unidentified planes on a wall-sized screen in Mexico City and to scramble interceptor aircraft if the planes entered Mexico.

Mr. Carrillo Olea, a former army general whom President Salinas appointed to oversee the drug intelligence center created with American help, was in charge of the radar system. American officials spoke highly of him, and many reacted with disbelief to the first intelligence reports that he was helping the traffickers.

But by 1992, additional reports persuaded analysts at El Paso's intelligence center that Mr. Carrillo Olea was helping Mr. Carrillo Fuentes. (The two are not related.)

As one intelligence document reads: ''Reporting from 1992 indicates that the former Mexican coordinator against narcotics trafficking, Jorge Carrillo Olea, was at that time Amado Carrillo Fuentes's most influential associate in the Mexican Government. Carrillo Olea was in charge of controlling the radar detection in Mexico, and by utilizing the information provided to him, he was able to insure safe passage of Carrillo Fuentes's aircraft.''

In an interview last week, Mr. Carrillo Olea, now Governor of Morelos, called these accounts ''a complete barbarity.''

''What can I say about a thing like this,'' he asked ''except that it is a rotund and absolute lie?It has no foundation whatever.''

American officials say that reports about Mr. Beltrones's drug activities have come from nearly two dozen sources inside the Mexican Government and its law enforcement agencies.

The 1994 D.E.A. study of Mr. Carrillo Fuentes described how his smuggling organization, identified by his initials, A.C.F., expanded ''full force'' into Sonora.

''Manlio Fabio Beltrones Rivera is well documented as being associated with the A.C.F. organization,'' the report reads. It quotes a commander of the Federal Judicial Police as stating that Mr. Beltrones is ''involved in protecting drug traffickers passing through Sonora.''

In 1994, Mr. Sears searched D.E.A.'s computerized intelligence files and found numerous references to Mr. Beltrones and members of his family, according to a memo Mr. Sears wrote. ''The Governor,'' the document noted, is mentioned in cases ''from San Diego to Tucson.''

A Source Network
Informers Describe Meetings and Money

Among the most persuasive intelligence reports, officials said, are accounts of regular meetings at a ranch in which Mexico's most notorious traffickers gave cash to Raul Salinas, who in turn distributed it to the senior politicians present.

Mr. Salinas, whose brother was President of Mexico at the time, is now awaiting trial in Mexico City on charges of murder and financial wrongdoing, and investigators have found more than $100 million in his overseas bank accounts. He maintains that his fortune has legitimate sources.

Mr. Beltrones was said to have attended three meetings at the ranch from 1990 to 1993, and the officials said Mr. Carrillo Fuentes was present for at least one.

In August 1994, the State Department sent William Francisco, a former Army infantry officer, to serve as the senior diplomat at the American Consulate in Hermosillo.

Almost immediately he trained his sights on the Governor, raising questions about the reports of corruption and misconduct, which were being ignored by other American officials.

Mr. Sears and his D.E.A. staff in Hermosillo were busy trying to keep track of the five major mafias operating all across northwest Mexico. They spent much of their time traveling between Hermosillo and the distant border gateways of Tijuana or Ciudad Juarez.

''They gave me a new car,'' Mr. Sears said, ''and I put 35,000 miles on it in seven months. We were just keeping our heads above water. There were so many reports of corruption about everybody that most of the time we didn't even write it up. We just had to accept the fact that corruption exists.''

In Pursuit
An American Consul Seen as Overzealous

Mr. Francisco felt otherwise.

Shortly after his arrival, he received a briefing from Mr. Sears about the major Mexican traffickers and studied the intelligence report naming Mr. Beltrones as an associate of Mr. Carrillo Fuentes.

Then, Mr. Sears recalled, Mr. Francisco traveled south to the state of Sinaloa and came back with new reports about the pervasive influence of traffickers. At his request, Mr. Sears checked D.E.A.'s computerized intelligence files and found extensive references to Mr. Beltrones.

In an unusual step for a State Department official assigned to an obscure consulate, Mr. Francisco began recruiting his own sources about the drug trade and Mr. Beltrones's role in it.

When Mr. Francisco heard a report that Mr. Beltrones was being considered for a post in President Zedillo's Cabinet as head of Mexico's powerful Interior Ministry, he grew downright alarmed.

On Nov. 15, 1994, after just 12 weeks as consul, he stalked into his office and fired off an urgent cable to the embassy in Mexico City.

''Request for assistance to verify and further develop info of allegations of extensive criminal activities by Son. Gov. Manlio Fabio Beltrones Rivera, who may be under consideration to become the next Secretary of Gobernacion,'' Mr. Francisco headlined his dispatch, using the Spanish term for Mexico's Interior Ministry.

Mr. Francisco complained that the D.E.A. and customs agents in Hermosillo were too preoccupied with minor traffickers and should instead pursue political figures like Mr. Beltrones, whom he termed ''a truly major kingpin player.''

His cable -- which mixed drug intelligence with lurid tales about the personal lives of Sonoran officials -- stunned Mr. Sears and officials at the embassy in Mexico City. Although Mr. Francisco had no direct or specific evidence to document his allegations, he called for a criminal investigation that could lead to Mr. Beltrones's indictment in the United States.

The cable reached the desk of the American Ambassador, James R. Jones, and American officials said he viewed it skeptically. Mr. Jones was instinctively cautious about the reliability of law enforcement intelligence reports. In addition, several officials said, the criminal investigation of a foreign official poses daunting political and practical difficulties.

Collecting intelligence on an official like Mr. Beltrones is one thing. But several officials said that building a criminal case against him -- linking him to specific drug shipments or conspiracies that violate American law -- would be quite another.

Informers willing to whisper an allegation under cloak of confidentiality would have to be persuaded to travel to the United States to testify before a grand jury, and perhaps later at a public trial. That would endanger not only their careers but their lives.

Even if all these difficulties were overcome, the accused official would have to be extradited to the United States for trial. Mexico has never before extradited a Mexican citizen accused of narcotics trafficking. (Juan Garcia Abrego, a Mexican trafficker, was expelled to the United States a year ago, not extradited, and he holds American citizenship.)

''Indicting a public official of a foreign government is cumbersome to say the least,'' the official said. ''And then getting them out of Mexico -- it never happens.''

Mr. Francisco's recommendation was never seriously considered by the embassy's top officials. Virtually everyone there reportedly regarded it as quixotic, even ''goofy,'' as one put it. In fact, officials said, the idea of launching an American criminal inquiry into Mr. Beltrones's dealings was not raised with senior officials in Washington.

A Revelation
List of Suspects For Mexico's Leader

As it happened, Mr. Zedillo and his advisers, preparing to take office on Dec. 1, 1994, had already given American officials a less public means of dealing with allegations involving officials like Mr. Beltrones.

''The Zedillo administration wanted names of people believed to be corrupt, or possibly in the pay of traffickers, whom the United States would not like to see in the new Government,'' a former American official said.

Mr. Jones gave Mr. Zedillo's transition team a list of about 15 current and former Mexican officials. It included Mr. Beltrones and Mr. Carrillo Olea, three officials said.

A senior Mexican official said in an interview that neither Mr. Beltrones nor any other of Mexico's 31 active governors was ever considered for a post in Mr. Zedillo's Cabinet. The Zedillo Government apparently has never followed up on the American warning by investigating either Governor.

But embassy officials felt that delivery of the list had shifted all responsibility onto Mexican authorities, where it belonged.

Early in 1995 the embassy's No. 2 official, David Beall, telephoned Mr. Francisco and lectured him about the cables he had written, American officials said. Mr Francisco interpreted the call in subsequent conversations with associates as an order to stop reporting on the Governor.

A senior American official denied that. ''He may have been told, 'For your own safety and for the integrity of what law enforcement is trying to do, don't be a cowboy,' '' the official said. ''But he was not muzzled.''

Still, if he stopped filing cables, Mr. Francisco continued to voice suspicions about Mr. Beltrones's activities. He even shared his opinions of the Governor with Nicolas Escalante Barrett, Mexico's consul general in Phoenix, who reported the incident to the Mexican Foreign Ministry. American officials and Mr. Beltrones said they believed that the Foreign Ministry complained to the American Government about Mr. Francisco's conduct.

In September 1995, Mr. Francisco was transferred to Frankfurt. He declined to be interviewed for this article.

One senior American official insisted that Mr. Francisco's transfer was a ''routine rotation.''

Others disagreed. ''He was a loose cannon,'' an official said. ''He was probably going to get himself killed if we didn't get him out of there.''

Mr. Carrillo Fuentes has continued to consolidate power. His success at sending cocaine-laden aircraft undetected into Mexican airspace and his largess have led Mexicans to nickname him Lord of the Heavens.

In January, Mexican troops stormed a ranch in Sinaloa during a wedding reception for Mr. Carrillo Fuentes's sister, hoping to capture him. But word leaked, and he slipped away. In the days that followed, authorities acknowledged that three private jets, operating without flight plans, had ferried wedding guests to Sinaloa from the airport in Cuernavaca, the capital of Morelos state, where Mr. Carrillo Olea is Governor.

American narcotics officials say that Mr. Carrillo Fuentes has been living in Morelos, where he owns many properties, and that his fleet of narcotics jets frequently lands and takes off unchallenged from the Cuernavaca airport. Mr. Carrillo Olea said in an interview that his aides had traced ownership of all residences identified as belonging to the trafficker, without finding his name. Any further investigation, he said, is the responsibility of federal authorities.

Mr. Beltrones is wrapping up his six-year term as one of Mexico's more popular governors. He is working closely with Gov. Fife Symington of Arizona on a plan to improve cross-border commerce and investment. Recent developments have left Mexico's anti-narcotics program in chaos.

The commander of January's failed wedding raid was Gen. Jesus Gutierrez Rebollo, then the national anti-narcotics coordinator. He was arrested last week and accused of having accepted payments from Mr. Carrillo Fuentes for seven years, ever since he was put in a command post in the anti-drug program.

Mr. Carrillo Fuentes's capture was intended as a dramatic symbol of progress in the drug war weeks before March 1. By that deadline annually, President Clinton certifies that drug transiting or producing nations are pursuing serious anti-drug efforts. Instead, the trafficker is still at large and still spending his billions.

''Money corrupts,'' said Doug Wankel, who just retired as D.E.A. operations chief, ''and in Mexico it's getting to the point where the traffickers can corrupt absolutely.''