A conservative group is suing the Bush administration for access to documents surrounding last fall's anthrax attacks, asserting that top officials may have known that the bioterrorist attack was coming.

Judicial Watch said Friday it has yet to receive documents from several agencies after filing requests under the Freedom of Information Act. The group argues the documents will show who knew what, and when.

Judicial Watch, which also has sued for documents about Vice President Dick Cheney's energy task force, represents U.S. postal workers at the Brentwood mail-handling facility in Washington. Two workers from Brentwood died of inhalation anthrax before officials shut down the facility, which had handled anthrax-laden letters headed to Capitol Hill.

Larry Klayman, chairman of Judicial Watch, noted administration officials said last fall that some White House staff had begun taking the antibiotic Cipro on Sept. 11, weeks before the anthrax attacks were made public.

"We believe that the White House knew or had reason to know that an anthrax attack was imminent or under way," Klayman said. "We want to know what the government knew, and when they knew it."

White House spokesman Gordon Johndroe denied it categorically. "We did not know about the anthrax attacks. Period!" he said.

Johndroe said he didn't know with certainty why staffers were given Cipro but guessed it was "a precautionary measure in the early hours of Sept. 11 before the situation could be fully assessed."

He said he has not seen the lawsuit and had no comment on whether the administration would release the documents.

Judicial Watch is suing the U.S. Postal Service, the Centers for Disease Control and Prevention, the FBI, the Department of Health and Human Services and the National Institute for Allergy and Infectious Diseases.

Federal agencies have come under fire for failing to realize that the postal workers at Brentwood were at risk for anthrax even after an anthrax letter was discovered on Capitol Hill and treatment had begun for Senate staffers. Health officials have said they did not realize then that anthrax could have escaped a sealed envelope.

Klayman said the mistake goes beyond a bad judgment call.

"They deliberately withheld information," he said. "The political elite, they'll be protected from day one. The ordinary folks will be treated in a lesser fashion."