Washington ? The Food and Drug Administration uncovered contamination and unsanitary conditions at a British flu vaccine manufacturing plant in 2003 but failed to re-inspect it until similar problems caused the loss of half the U.S. vaccine supply in October, the top FDA official said Wednesday.

FDA inspectors who visited the Chiron Corp. plant in Liverpool in June 2003 found records of bacteria concentrations a thousand times the expected level, said a report distributed by Democrats at a hearing of the House Government Reform Committee.

The preliminary inspection report from last month indicates in three places that deficiencies found in 2003 had not been corrected.

But acting FDA Commissioner Lester Crawford said the problems in 2003 and those that tainted this year’s vaccine were unrelated. “The proof of that is that the 2003 vaccine production was completed on schedule and none of it was condemned,” Crawford said.

Rep. Henry Waxman, D-Calif., said Crawford’s assertion was part of a “pattern of misleading statements.” The FDA might have averted or at least mitigated the vaccine shortage if it had been vigilant, Waxman said.

Instead, he said, the FDA rejected the recommendations of its inspectors for a formal warning to Chiron and asked the company to correct problems voluntarily.

Even after Chiron indicated on Aug. 25 that several million doses of vaccine had been contaminated, Waxman said, the agency remained passive, relying on weekly conference calls with the company rather than a new inspection.

“My criticism is that the FDA didn’t do enough to stay on top of this,” he said in one of several tense exchanges with Crawford.

British health authorities suspended Chiron’s license on Oct. 5, citing manufacturing problems at the Liverpool plant. The company had been expected to ship roughly 50 million doses of its Fluvirin vaccine to the United States.