Immigration inspectors jailed an innocent Chinese businesswoman for two nights after rejecting her passport Saturday, following earlier promises to avoid jailing travelers in all but aggravated cases.

U.S. Immigration and Naturalization Service managers defended their actions Tuesday after letting Guo Liming resume her trip to New York via Portland International Airport. They said they considered the case aggravated because Guo, 36, appeared typical of Chinese sneaking into the United States. They blamed her for not replacing a passport that looked doctored but turned out to be authentic.

Guo said INS inspectors made her strip to her underwear for a search. They interrogated her under oath through an interpreter. Then they handcuffed her for the two-hour drive to jail in The Dalles. "They owe me an apology," she said.

The jailing revived nagging questions concerning INS conduct at the Portland airport, where inspectors reject a far higher percentage of foreigners than are turned away from other West Coast airports. Last January, Guo used the same passport to enter the United States without incident in Los Angeles.

Many Asian companies and travel agents continue to advise travelers to avoid Portland, hurting sales for Delta Air Lines, despite INS promises of reforms, such as substituting guarded hotel rooms for jail cells. Japanese newspapers published a story this month by Kyodo, a Japanese wire service, that reiterated the problems without mentioning the reforms.

The controversy could end shortly if Delta grounds its remaining flights between Portland and Japan, as airport managers think likely, leaving PDX without overseas air service. Increased competition and long-range planes are the main culprits, Port of Portland officials say, not fallout from the INS controversy.

Guo arrived in Portland Saturday on a flight from Japan with Hsieh Tsuhui, 43, her fiance and business partner. The couple planned to proceed to New York on business.

Guo, a resident of Guangzhou, China, handed her passport to an INS inspector, who found it suspicious.

"It had all the outward appearances of the kinds of bogus documentation we've seen in the past presented by PRC nationals," said David Beebe, INS district director in Portland. "China has been a problem to PDX in terms of either photo-substituted passports or fraudulent visas."

Beebe said the passport's original clear plastic laminate had been peeled back, causing inspectors to think that a photo had been substituted and a second laminate applied. Guo also "fit the profile" of attempted illegal immigrants, Beebe said, because she was traveling with another person. In the past 19 months, Portland has had nine such cases, said John O'Brien, INS port director.

The inspectors began processing Guo for "expedited removal," preparing to place her on a return flight to Japan. They sent photo scans of the passport to an East Coast forensics lab for analysis by experts.

"About six of these federal experts apparently agonized and discussed at length their observations," Beebe said. The experts attributed the double lamination to "a very poor job of quality control" at the Chinese passport office.

On Monday, they told Portland INS inspectors that the passport was valid. Guo was released from the Northern Oregon Regional Corrections Facility in The Dalles, where the agency sends its detainees. She was driven back to the airport and admitted to the United States. Airport immigration officials have jailed six or seven foreigners in aggravated cases since arranging for hotel rooms June 1.

"At the jail, they had kept $1,300 that I was carrying in cash," Guo said. "When they released me, they gave me a check for that amount.

"I've gone to three banks, but they refuse to cash it because I'm not a resident."

Guo said no one ever apologized to her. O'Brien said inspectors apologized profusely Monday night.

But Tuesday, Beebe said Guo should have replaced her passport after encountering problems with it earlier in Hong Kong. "If I had that problem, I sure the hell would have taken care of it," Beebe said. He said inspectors confronted with a similar case in the future would follow exactly the same procedures.

Beebe could not explain why immigration inspectors in Los Angeles would have accepted Guo's passport. And it was unclear Tuesday whether Guo's problems in Hong Kong occurred on her current trip or earlier.

Guo did not have time to describe her Hong Kong experience during an interview with The Oregonian on Tuesday as she hurried to catch her flight to New York. A calm, poised woman, she spoke with bitterness but self-control of her ordeal, during which she said she was chained as well as handcuffed.

Guo declined to disclose her company name or the nature of her business, saying that the firm wouldn't want the publicity. She hesitated to talk to a reporter for fear of retribution by the INS, but said she planned to carry the article with her on future trips as a means of explanation.

Guo said that she was unable to contact a lawyer, the Chinese consulate or anyone outside the jail during the weekend. Hsieh, her fiance, didn't know where she was until Monday morning when he hired Bao Lin Chen, a Portland immigration lawyer, to find her.

"They asked me whether we have any human rights protection," Chen said. "That's a kind of question a person asks in China, not this country.

"It wasn't her mistake, but she was treated like a criminal."