British health officials said Friday that their American counterparts were informed in mid-September that problems at a drug manufacturing plant in northwest England could disrupt influenza vaccine supplies to the United States.

Records at Britain's Department of Health show that the plant's owner, Chiron Corp., warned officials of the U.S. Food and Drug Administration and the British Medicines and Healthcare Products Regulatory Agency on Sept. 13 that potential contamination problems remained unresolved at the plant, according to Alison Langley, a senior spokeswoman at the department.

The British account is at odds with statements by U.S. health officials that they were caught by surprise by the British regulatory agency's decision this week to suspend vaccine manufacturing for three months at the Liverpool plant. It had been expected to provide 48 million doses of flu vaccine to the United States, about half of the U.S. supply this year.

Unlike the United States, health officials in Britain responded to the warning by making "plans by contacting other manufacturers," Langley said.

In Washington on Friday, federal health officials told an emergency hearing in the House Committee on Government Reform that the system for procuring vaccines for the American public has been getting increasingly fragile for years but that none of the proposed solutions are likely to fix the problem quickly.

British officials said there had been regular communication with American public health officials at the FDA and the Centers for Disease Control and Prevention since Aug. 26, when Chiron announced it would delay releasing supplies of the vaccine because about 4 million doses had been tainted.

Jason Brodsky, an FDA spokesman, provided an agency statement disputing the British account, saying: "None of the Center for Biologics Evaluation and Research (CBER) staff who were in regular communication with Chiron since August 25, 2004, were notified by Chiron that there was an increased level of concern regarding the company's investigation of the bacterial contamination."

Furthermore, according to the statement, there had been no communication between CBER and the British agency until that agency suspended Chiron's license. That decision was reached last weekend, and Chiron was informed Tuesday, according to congressional testimony this week.

Britain had been scheduled to receive about 2 million doses of the vaccine, known as Fluvirin, or 10 to 20 percent of its total need.

A British Department of Health statement said officials had already arranged for an additional 1.2 million doses from some of its five other suppliers by the end of the month, with an additional 1 million due to arrive by mid-November.

U.S. officials, by contrast, have said they might not be able to make up the shortfall and urged doctors to give the vaccine only to people who are at highest risk. Influenza kills about 36,000 Americans each year, and as many as 500,000 people worldwide.

A senior British official disclosed this week that the initial cause of the contamination was Serratia marcescens, a potentially dangerous bacterium.

A microbe with a distinctive red pigment, Serratia marcescens is spread by contact with contaminated hands or equipment and was once thought of as harmless, according to Melanie Scourfield of the Society of Microbiologists here.

"It's an opportunistic pathogen that lives in soil and water and has been linked to hospital-acquired infections, dialysis infections and pneumonia," she said.

The Liverpool plant, which Chiron purchased last year, has gone through a series of owners and technical problems in recent years, according to British news reports. In 1999, FDA inspectors accused one of its previous owners, Medeva, of failing to ensure that the plant's systems and equipment for producing Fluvirin were free from contamination.

The following year, British health officials ordered polio vaccines that were manufactured at the plant in 1996 to be withdrawn because of possible contamination with the misformed proteins that cause mad cow disease. And in 2002, Irish officials suspended sales of BCG, a tuberculosis vaccine made at the plant, because of concerns that it was below required strength.

Medeva was bought in January 2000 by Celltech, which later sold its vaccine business to PowderJect Pharmaceuticals, a British-based firm that in turn sold the plant to Chiron.

"This plant has been well known in the industry," said a British pharmaceutical executive who spoke on condition of anonymity. "It's passed through a lot of companies' hands very quickly. . . . One or two companies who have owned this plant -- perhaps they haven't spent the money on it they should have done, while milking it pretty hard."

Chiron's corporate communications headquarters in Emeryville, Calif., did not return a reporter's phone calls on Friday.

Company officials previously have denied that they sought to expand the plant's production capacity too rapidly and said they had spent $75 million to upgrade the facility.

British health experts said U.S. officials should have realized the potential scale of the plant's problems and taken steps to locate other suppliers.

"The American policy has been cruelly exposed -- their decision to put all their eggs in one basket, so to speak," said John Oxford, an international expert on influenza at Queen Mary's College in London.

"But perhaps this will be a good wake-up call and an encouragement to the American government to think again about how they are going to manage flu. It is urgent that we increase production, because there will be a flu pandemic sometime in future years."

Michael Langman, chairman of the Joint Committee on Vaccination and Immunization, an independent expert advisory committee, said Britain was wise to line up a half-dozen suppliers. "You have to take the approach that it is always possible that something could go wrong with a company's vaccine," he said. "The probability is that it won't, but the possibility is there."

Staff writer David Brown in Washington contributed to this report.

The Chiron vaccine factory in England produces the flu shot. The plant may have contamination problems, which will halt supplies of the vaccine.