Rep. Henry A. Waxman (D-Calif.) said this week that an insider at the Food and Drug Administration told him the agency was withholding documents sought by Congress addressing whether the FDA could have prevented the shortage of flu vaccine.

According to Waxman, the unidentified FDA employee recently contacted him and claimed that an array of materials had been prepared for public release by the end of last week but that an FDA official decided to keep them under wraps until after the Nov. 2 presidential election.

The documents relate to the FDA's oversight of a flu vaccine factory owned by Chiron Corp., which British regulatory officials shut down earlier this month.

"These are serious allegations," Waxman wrote in a letter Tuesday to Lester M. Crawford, acting commissioner of the FDA. "Public health, not political expediency, should be guiding FDA's actions."

Waxman's staff provided no further details about the source of the information.

In a statement late Tuesday, Crawford said the FDA had not finished collecting the documents. Responding to the vaccine shortage "remains our most immediate public health priority" and "FDA staff are working diligently to provide a complete response to all of the Committee's questions," he said.

The U.S. government's oversight of the Chiron vaccine factory in Liverpool has become an increasingly sensitive political issue since British health authorities shut down the plant on Oct. 5, slashing this country's expected vaccine supply for the coming flu season.

An FDA inspection in June 2003 found signs of bacterial contamination at the plant, leading some to question whether U.S. regulators followed up effectively to make sure the problems had been solved. The factory's current problems also involve contamination, which Chiron first discovered in August.

The flu issue has also flared up on the presidential campaign trail. The Democratic candidate, Sen. John F. Kerry (Mass.), has argued that it is a failure of the Bush administration, while the president recently sought to reassure an audience in Florida that the administration is doing all it can to make sure there will be enough vaccine for those who need it.

Republicans in Congress have suggested that Waxman is more interested in seeking political advantage for Democrats than in the vaccine shortage itself.

Rep. Henry A. Waxman (D-Calif.) said documents are being withheld.