The Bush administration is to announce a series of policy changes today that it says will give the federal Occupational Safety and Health Administration more power to crack down on companies that persistently flout workplace safety rules.

Under the new policies, OSHA officials will be directed to conduct more follow-up inspections of companies that commit safety violations of "the highest severity," according to a memorandum obtained by The New York Times.

Companies that fail to correct violations will in some cases find themselves facing contempt of court orders from federal judges to force action. The legal threat will be buttressed by a better-coordinated enforcement approach on the part of OSHA inspectors, who will be required to link more thoroughly incidents at all work sites owned by the same "overall corporate entity."

Currently, follow-up inspections are relatively rare, contempt orders are all but unheard of and there is little effort to coordinate inspections of large, complex corporations that have work sites spread across several states, often operating under different corporate names.

In an interview yesterday, John L. Henshaw, the OSHA administrator, said that the changes had been prompted by a recent New York Times series examining McWane Inc., a major manufacturer of cast-iron sewer and water pipes that has one of the worst workplace safety records in the United States.

The series reported that McWane, a company in Birmingham, Ala., that employs some 5,000 workers in a dozen American plants, had been cited for more than 400 safety violations since 1995, far more than all of its major competitors combined. During that time, records show, McWane employees suffered at least 4,600 injuries. Nine workers were killed, three of them because of McWane's deliberate violations of federal safety standards, OSHA inspectors concluded.

"There are those who, despite OSHA's enforcement and outreach efforts, continually disregard their very basic obligations under the Occupational Safety and Health Act," Elaine L. Chao, the labor secretary, said in a statement released yesterday. "This enhanced enforcement is meant for them."

Mr. Henshaw said the policy changes were aimed at one of the most glaring regulatory deficiencies highlighted by the McWane example. As OSHA's own investigation files showed, McWane workers have been maimed, burned and killed year after year by the same patterns of safety and health failures. Yet regulators in far-flung offices never joined forces, either to recognize or end these patterns. Their disjointed responses allowed McWane's conduct to go largely unchecked.

The policy changes, which can be carried out directly, without alterations in law or regulation, will put "more teeth" into OSHA's ability to police companies that continually defy workplace safety rules, Mr. Henshaw said, adding that the changes will not require new money or inspectors. "We have been looking at ways to be more serious and more tenacious," he said.

But he stopped short of endorsing even tougher measures that some members of Congress have proposed to prevent more of the kinds of deaths that have been documented in McWane plants and elsewhere.

Senator Jon Corzine, Democrat of New Jersey, circulated a letter to other senators last month seeking support for a proposed Wrongful Death Accountability Act, which would increase to 10 years from 6 months the maximum criminal penalty for employers who cause the death of a worker by willfully violating safety laws.

Asked whether he supported Mr. Corzine's proposal, Mr. Henshaw replied, "We have no position."

OSHA has already begun to apply elements of the new policies in its dealings with McWane; inspections are under way at several McWane plants. But the policy changes could have even more significant consequences for other major American corporations with high injury rates.

The United Parcel Service, for example, has 178 work sites on OSHA's list of some 14,000 workplaces with the nation's highest injury and illness rates, records show. Under the new OSHA policy, an egregious safety violation, such as one that caused an employee's death, would bring on automatic inspections at all 178 work sites.

"It puts the corporate entity on notice that if we have a high severity violation, then they become a focus of the agency," Mr. Henshaw said of the policy change, estimating that hundreds of workplaces could expect to face closer scrutiny. "It creates a certainty that we will be there."

But some workplace safety advocates said that although the policy changes were welcome, they did not begin to address deeper structural weaknesses at OSHA, including the fact that the fines it imposes on transgressors have been raised only once in its 32-year history.

"The idea of trying to focus on employers who are failing to abate and are repeat violators is not a bad idea," said Margaret Seminario, director of safety and health for the A.F.L.-C.I.O. "However, what seems to be missing in this policy is enhanced enforcement."

Citing her analysis of OSHA's fines during the Bush administration, Ms. Seminario said the average fine for a willful safety violation had decreased by 26 percent, to $26,888 in 2002 from $36,487 in 2000. The average fines for companies that fail to fix safety violations have decreased 68 percent, to $2,448 in 2002 from $7,687 in 2000 , she said.

"For repeat and persistent bad behavior, they are not proposing changes in the citation and penalty structure that would treat these employers any differently," Ms. Seminario said.

But others said that in instituting the changes, Mr. Henshaw was walking a fine line in an administration that has made no secret of its overall distaste for tighter business regulations.

"Henshaw cannot say what he thinks because of the administration," said Patrick Tyson, an OSHA administrator under Ronald Reagan. "Business would not understand going to a felony," he added, referring to Mr. Corzine's proposal.

Mr. Tyson, though, is among many experts across the ideological spectrum who say they believe that the worst employers will not take OSHA seriously unless they face a lengthy prison term for killing a worker through indifference to safety rules.

"Six months is nuts," Mr. Tyson exclaimed.

Now an Atlanta lawyer who consults with several Fortune 500 companies on workplace safety issues, Mr. Tyson said his law firm was recently retained by McWane to "turn their safety program around." He said his firm and other outside consultants were interviewing supervisors, managers and executives at every McWane plant.

"They seem to be real," Mr. Tyson said of the changes at McWane.