MANILA, NOV. 7 -- The United States has accepted one of Manila's major demands in the current base negotiations, announcing today that it would remove all its fighter aircraft from the Philippines next year.

Richard Armitage, the U.S. diplomat charged with negotiating an agreement with the Philippine government on the future of Washington's bases here, told Foreign Secretary Raul Manglapus of the decision when he arrived in Manila.

"The net effect of this decision is that at some point in 1991, the U.S. will have no fighter aircraft permanently based in the Philippines and that more than 1,800 U.S. military personnel will have departed," a U.S. Embassy statement said.

Armitage is in Manila for a round of talks on the bases that will begin Thursday and are scheduled to last until Friday evening.

Philippine officials have said Manila wants full sovereign control of Clark Air Base and four smaller facilities by September 1991.

It would accept a later date for control of Subic Naval Base, the main ship repair and maintenance facility of the U.S. 7th Fleet.

U.S. officials have said they hope to keep access to the Crow Valley training range at Clark and to military transport facilities there, perhaps on a commercial basis.

Manglapus welcomed the U.S. announcement. "It's certainly a step forward. Before the announcement we thought we'd have to argue about it," he told reporters.

The U.S. statement said the decision was not purely related to the talks.

"The notification to Foreign Secretary Manglapus makes it clear, however, that this decision was influenced, though not dictated, by the government of the Philippines' publicly expressed position that the fighters should be removed by September 1991," it said.

"The decision was based on an assessment of where best to allocate highly valuable resources to maintain our long-term commitments in the region," it added.

Western diplomats said Washington might have gained negotiating strength by showing that it was prepared to leave the bases if made to feel unwelcome by Manila.

The bases employ about 80,000 Filipino workers and inject about

$1 billion a year into the Philippines' struggling economy.

Manglapus said many questions remained to be negotiated. "The Americans want it {ability to use the bases} as long as possible, and the Philippines want it as short as possible," he said.

President Corazon Aquino has said she wants an agreement by January 1991.

Fighter jets from Clark flew missions in support of Aquino during the sixth and bloodiest coup attempt against her, in December 1989.