A public interest group yesterday filed suit to block a controversial federal proposal to use unapproved drugs to protect troops in the Persian Gulf against chemical and biological warfare.

The Pentagon worked out the arrangement last month with the Food and Drug Administration, which will allow the military to give troops the drugs without first informing them of the risks and obtaining their consent, as is usually required by law for experimental therapies.

The Pentagon argued that obtaining such individual consent from troops stationed in the gulf would not be "feasible in certain battlefield or combat-related situations."

In a complaint filed yesterday in U.S. District Court here, the group Public Citizen asked that the agreement be struck down and the military be required to obtain permission from all those given the drugs.

"As a physician, it is difficult to emphasize how strongly I condemn this regulation and its departure from that which is moral, ethical and legal," said Sidney Wolfe, director of Public Citizen's Health Research Group.

"Even though someone is in the military, the law requires that they be treated as a human being, not stripped of their right to refuse experimental drugs, which can pose unknown risks and be of questionable efficacy."

Federal officials reacted angrily to the suit, stressing that any unapproved drug given to soldiers would be carefuly screened first by the FDA to make sure that it posed no health risk.

"This is an outrageous attempt to divide our troops and our country by wrongfully suggesting that we are unconcerned about the health and safety of our soldiers," said FDA spokesman Jeffrey Nesbit. "These drugs will save lives and ease pain."

Some medical experts said the informed-consent waiver granted to the Pentagon was the only practical way for the Defense Department to ensure that troops in the gulf are adequately protected against chemical and biological warfare.

"This is not like a laboratory situation where a person is being interviewed as to whether he or she would like to be a research subject and if the person says no they can go on with their life," said Yale University medical professor Robert Levine. "It's not as if you can continue to be a member of the infantry in Sauia Arabia and refuse this vaccine. You'll die."

Wolfe said the Pentagon is asking for permission to give troops three drugs. The first is a vaccine against the powerful poison botulin, suspected to be among the biological agents in Iraq's arsenal. The vaccine has been used by government laboratory scientists working with the toxin for almost 20 years.

The second drug is pyridostigmine, a tablet that is currently approved only for treatment of neuromuscular disorders. The military would like to use it -- at half the regular dose -- as an antidote to nerve gas, Wolfe said.

The third drug is a skin cream used to protect factory workers from industrial chemicals. Wolfe said the Pentagon wants to use it to protect troops against mustard gas. Though currently in commercial use, the cream is sold as a cosmetic. The FDA considers it a drug and has not approved its use as such.

Some experts suggested that these products have not been approved for wartime use less because of concerns about health risks than because until now there has not been a market for them.