Nearly 20 percent of U.S. Food and Drug Administration scientists surveyed in late 2002 said they were pressured to approve or recommend approval of a medicine despite their reservations about the drug's risks or effectiveness, according to documents made public on Thursday.

Also, two-thirds of the scientists questioned by the Department of Health and Human Services' inspector general said they lacked full confidence in the FDA's ability to monitor side effects of prescription drugs after they hit the market.

The survey shows at least some government scientists backed accusations last month by FDA safety officer Dr. David Graham, who told a Senate hearing he was pressed to water down safety concerns about Merck & Co. Inc.'s painkiller Vioxx. The drug was pulled from the market Sept. 30 over links to heart attacks and strokes.

Graham, associate director for science in the FDA's Office of Drug Safety, also told Congress he felt the FDA was incapable of protecting the public from other dangerous drugs.

The survey of nearly 400 FDA scientists was obtained through the Freedom of Information Act by the Union of Concerned Scientists and Public Employees for Environmental Responsibility, two environmental activist groups.

"The scientists' concerns warrant further investigation as Congress reviews drug approval practices at FDA," said Kathleen Rest, executive director of the Union of Concerned Scientists, which has Nobel-prize winning researchers as well as activists as members.

An FDA spokesman did not immediately return a call seeking comment.

Among other findings, 36 percent of the FDA scientists said the were "not at all" or only "somewhat" confident that "final decisions adequately assess the safety of a drug."

Portions of the survey were published in a March 2003 inspector general's report about the FDA's review process. But the negative opinions often were downplayed in favor of a focus on positive findings, Rest said.

The inspector general's report did note that many reviewers felt time-pressured, and 58 percent said the six months allotted for a priority drug review was inadequate.