JAMBA, ANGOLA -- U.S.-backed Angolan rebel leader Jonas Savimbi, in an apparent bid to accelerate peace negotiations, said he will no longer demand formal recognition of his movement by Angola's ruling party and will agree to a cease-fire "immediately" if it legalizes opposition parties in general.

Speaking to reporters at his bush headquarters in southeast Angola, Savimbi said Wednesday that if the ruling party's third congress, now meeting in Luanda, the capital, approves an amendment to the Angolan constitution permitting multi-party politics, then "we are satisifed."

"If they approve the multi-party system now," he said, "then at the next round {of negotations} what we do is sign a cease-fire."

A sixth round of Portuguese-brokered negotiations, in which both the United States and Soviet Union are observers, is scheduled in Portugal in mid-January.

"I'm not asking for recognition of UNITA," Savimbi's National Union for the Total Indpendence of Angola, "but for all parties," he added. "If they do that, UNITA has no reason not to sign a cease-fire."

"If they don't want to recognize UNITA alone because they feel this will give UNITA an edge over other parties, they should decide now at this congress that the multi-party system can be started now," he said.

Savimbi's stated readiness to drop a principal demand appeared to be timed to coincide with the party congress, at which President Jose Eduardo dos Santos is seeking formal approval of establishing a multi-party system.

Hard-liners of the ruling Popular Liberation Movement of Angola are reported to be opposed to both the legalization of other parties after 15 years of single-party rule and formal recognition of UNITA.

Asked how soon a cease-fire could be signed, Savimbi replied, "Immediately," apparently referring to the next session of talks. But he went on to say UNITA had to have "guarantees" in the form of United Nations monitors of the cease-fire before it would end its 15-year guerrilla war.

Savimbi said a U.N. monitoring group was "the only guarantee" UNITA would accept in return for ending hostilities because he anticipated an immediate cutoff of U.S. covert military assistance, reportedly set at $60 million this fiscal year.

U.S. and Soviet officials reportedly have agreed informally to halt arms shipments to their respective allies.