Members of West European parliaments told the Senate Foreign Relations Committee yesterday that their countries support the new U.S.-Soviet nuclear arms-reduction treaty and warned that rejection of the pact would jeopardize NATO and revive pressures for unilateral disarmament.

Even if the Senate does not ratify the treaty, there is no guarantee that West Germany would continue to deploy U.S. intermediate-range missiles that are targeted for elimination under the pact, said Karsten D. Voigt, the Social Democrats' foreign policy spokesman in the West German Bundestag.

The lawmakers, members of the North Atlantic Assembly, the inter-parliamentary arm of NATO, described as vastly exaggerated the claims by treaty critics that European leaders are more critical of the pact in private than they are in public.

It has "very considerable support right across the political spectrum in Europe," said John Cartwright, a Social Democratic member of the British House of Commons.

The Intermediate-Range Nuclear Forces Treaty has a 90 percent approval in public opinion polls in West Germany and is supported by all members of the Bundestag, Voigt said.

Francois Fillon, a Gaullist deputy in the French National Assembly, expressed stronger reservations than the others about the pact but endorsed it and warned that its rejection would have "grave political consequences in Europe."

Ton Frinking, a member of the Netherlands parliament and president of the North Atlantic Assembly, said rejection would be a "disaster for the {NATO} Alliance."

Despite their agreement on the need for ratification of the INF Treaty, the Europeans disagreed among themselves on deployment of new battlefield nuclear weapons and on whether the United States should reverse its position and push ahead with negotiation of a treaty to ban them as well.

Voight said none of the parties represented in the Bundestag supports deployment of the short-range missiles on grounds that "the shorter the range, the deader the Germans."

But Fillon said it is "absolutely essential" that nuclear forces be modernized and upgraded, including the possibility of future joint weapons ventures by the British and French.

While acknowledging "differences on this issue" among West European countries, Frinking said negotiations to achieve balanced reductions can occur without insisting on total elimination of all nuclear weapons.