President Bush's top advisers are recommending that he veto legislation requiring a one-year cutoff of U.S. trade with companies that aid development of chemical and biological weapons in Iraq and other nations, according to senior U.S. officials and congressional sources.

The legislation was approved by Congress last weekend despite strong administration protests that it would hamper U.S. flexibility and prevent a case-by-case determination of suitable punishment for private firms and countries that use poison gas or germ warfare in combat.

An administration official said that while Bush has not announced his decision, "the feeling is that the president should veto it, and likely will veto it" due to concerns that it will impinge on his future discretion in conducting foreign policy.

The State Department opposes the legislation, spokesman Margaret Tutwiler said yesterday, as does White House national security adviser Brent Scowcroft. Tutwiler said its mandatory provisions for unilateral sanctions "would constitute objectionable intrusiveness into executive branch prerogatives and be potentially fatal to our efforts to cooperate with friends and allies" on such measures.

In a letter Friday, 59 House members urged Bush to sign the legislation, which the Senate had approved with even stiffer requirements by a 92 to 0 vote one week before Iraq's Aug. 2 invasion of Kuwait. "Where we differ," the members told Bush, "it is due to sentiment here that to overly 'condition' the application of sanctions is to weaken their deterrent effect."

Senate Foreign Relations Committee Chairman Claiborne Pell (D-R.I.), a principal sponsor of the legislation, said yesterday that "with American soldiers facing chemically armed Iraqi forces across the Saudi desert, I find it incredible that some in the administration continue to oppose mandatory sanctions against countries that use chemical weapons."

He said that if Bush kills the legislation in a "pocket veto," it would be introduced again next year and passed with enough support to override another veto. A pocket veto, which cannot be contested, occurs if Bush decides not to sign the legislation while Congress is not in session.

"I think it's sending precisely the wrong message . . . concerning this president's commitment to stopping the spread of chemical and biological weapons," said Elisa Harris, a Brookings Institution analyst. "We should learn from the mistakes we made during the {1980-88 Persian} Gulf War, when we ignored Iraq's use of chemical weapons {against Iran}, and we should draw a clear line in the sand now."

Supporters of the legislation say it was motivated partly by revelations of extensive Western assistance to chemical weapons programs in Iraq and Libya, and partly by what they say was a tepid worldwide response to Iraq's past use of poison gas in the Middle East.

Although U.S. criticism prompted the government of West Germany to begin prosecuting some companies that aided the Iraqi program, the firms were not barred from signing U.S. government contracts or shipping goods here. Before Iraq's seizure of Kuwait, the administration also opposed invoking trade sanctions against Iraq on grounds that firms in other nations would grab the business.

Virtually all trade between Iraq and other nations was halted under a U.N. resolution approved shortly after the Kuwait invasion.

The administration had favored a House-passed provision allowing a presidential waiver of the sanctions on national security grounds, but the tougher language of the Senate bill was adopted by a conference committee. House Foreign Affairs Committee Chairman Dante Fascell (D-Fla.) is among those now urging Bush to sign the bill, according to congressional aides.

The legislation subject to veto also includes a reauthorization of constraints on U.S. exports of militarily sensitive technologies, which could also be affected by Bush's action.