The Arab-sponsored move to bar Israel from the International Telecommunications Union was thwarted at the last minute by a British parliamentary maneuver.

Arab members had sponsored a resolution, known as document 120, condemning Israel for its recent invasion of Lebanon and the massacre of Palestinians in two refugee camps and demanded Israel's ouster. But in a late move after nearly six weeks of wrangling over the resolution, the British sponsored an amendment that offered a substitute for the expulsion paragraph.

In its place the British amendment, cosponsored by seven Western countries, sharply condemned Israel for its actions in Lebanon but dropped the call for Israel's exclusion from the ITU.

Toward the end of a four-hour voting session by secret ballot that concluded early today, the amendment passed 61-57, and then the whole resolution was easily adopted, 85 to 31 with 13 abstentions.

The new wording, which effectively protects Israel's credentials in this U.N. agency that governs international cooperation in telecommunications, is perceived by observers as an important victory for Britain and the United States. Washington threatened to walk out of the conference and suspend the annual $3.2 million U.S. funding of the ITU if Israel was barred from the conference.

The head of the U.S. delegation here, Washington attorney Michael Gardner, told reporters: "Tonight you saw a very democratic process that decided the U.N. system should stay intact. I would presume this vote is very clear to people who would like to use the Israeli issue to spoil the U.N. system."

The resolution fight had become a test case for U.S. influence in U.N. forums, following Secretary of State George P. Shultz's warning early this month that Washington would withdraw from any U.N. bodies from which Israel was expelled. Gardner said a basic principle involved in the U.S. stand was Washington's opposition to the politicization of such technical bodies as the ITU.

In a statement after the vote, Israel's chief delegate, Michael Shakked, condemned the resolution, saying it "contains false accusations against Israel. It makes factual and legal determinations which are untrue and have no legal basis."