The 35-nation conference on European security and cooperation was saved from the brink of collapse when the Soviet Union accepted a last-chance compromise to keep the sessions going beyond today.

The Soviet acceptance came after 10 weeks of haggling here on an agenda for this follow-up conference on the East-West agreements on human rights and military detente in Europe signed in Helsinki in 1975. The compromise, drafted by several neutralist nations, called for curtailment of debate on human rights violations and accept instead a follow-up meeting reserved for new proposals on detente.

The first hint of Soviet willingness to compromise came in the moderate tone used by Soviet Deputy Foreign Minister Leonid Ilichev in a speech to the conference today. He had been expected to make a strong counterblast to a U.S. address yesterday denouncing the invasion of Afghanistan and a long list of human rights violations in the Soviet Union and Eastern Europe.

Illichev's immediate reaction to the speech by former U.S. attorney general Griffin Bell came in an angry statement he made to the Madrid newspaper El Pais saying that the U.S. statement was "full of lies and slanders" and that Bell had spoken at length about human rights "because the United States does not want to talk about peace."

Today, however, the Soviet representative said his country had accepted the compromise because "we have heard the voice of the people, and the people want peace and detente." This seemed to imply Soviet recognition that the breakup of the conference could have had an incalculably negative effect on the international atmosphere.

When the Soviets announced acceptance of the compromise to a special closed-door working group late this afternoon, participants said there was a spontaneous burst of applause.

"It's the first time I've seen that group smile," said a U.S. delegate.

U.S. Ambassador Max Kampelman said the applause was "a release of tensions." He said he and the Soviet ambassador shook hands and "exchanged pleasantries -- none of us look at this in personal terms. We all know there are important issues of principle involved."

Kampelman speculated that the Soviets decided to let the conference, which operates by unanimous consent, continue because Soviet leader Leonid Brezhnev is so heavily identified with the Helsinki accords that it would have been a blow to his prestige to put an end to the furtherance of detente through those agreements.

The Soviet delegation's acceptance of the compromise was clearly directed from Moscow.When the compromise proposal, announced last night, was formally submitted to the working group after noon today, the Soviets asked for and got a five-hour recess. Illchev reportedly told the Swedish foreign minister that he had to call Moscow but that he would recommend acceptance.

The neutrals who proposed the compromise -- Austria, Cyprus, Sweden and Yugoslavia -- said that any country that refused it would have to bear the responsibility for the breakup of the conference. The Soviet move seems to indicate unwillingness to risk taking the blame.

The compromise calls for continuing the conference for five more weeks after the week's round of initial statements by each of the 35 participants, and continuing during that time to examine the records of compliance with the Helsinki accords of the signatories.

During that period the West will be free to raise Soviet and other human rights violations of the Helsinki agreements. The conference will then recess Dec. 19 and will reconvene for six weeks starting in late January only to consider new proposals to further detente. In that phase, the West has agreed not to raise any violations that took place before the adjournment of the first half of the conference.

But, Kampelman said, it is understood that if something happens during the Christmas break that would be covered by the Helsinki agreements, the United States would feel free to raise it. He apparently had in mind the tense situation in Poland and widespread fears that the Soviets might intervene there.

The U.S. delegation refrained from claiming victory, and Ilichev called the compromise a victory for "reason and common sense."

Kampelman indicated that today's Soviet action has still not cleared the air for any new proposals the Soviets might now want to make.

One such project the Soviets have been interested in is calling a European conference on military detente, which would deal with such measures as freezing the membership of the Atlantic Alliance and the Warsaw Pact, thus preventing Spain from joining NATO.

"We believe it is somewhat ludicrous that such a proposal should be made while Soviet troops are in Afghanistan," Kampelman told a post-compromise press conference.

He said that one of the most encouraging results of Soviet tactics here was the recementing of the 15-nation NATO caucus and the addition of Spain as a 16th member.

Kampelman described the past 10 weeks as having followed the "traditional Soviet negotiating pattern of not rushing, taking your time, delaying, getting involved with technicalities and minutiae."

Earlier he had said that new-found Western unity here had not come at the price of reinforced Warsaw Pact unity. The East European speeches seemed to bear him out, with only Czechoslovakia and East Germany taking clearly hard-line positions and Hungary, Poland and Romania indicating in various ways their reservations about the Soviet line.

Romania went so far today as to propose its capital of Bucharest as the site of the next follow-up conference on the Helsinki accords in two or three years, even though the Soviets have clearly indicated that they do not want another conference to be scheduled at all.

Polish Deputy Foreign Minister Marian Dobrosielski said that the free trade unions are "a movement directed not against the basic constitutional framework of our state and society, not against socialism, but against its deformations."