For this capital's dwindling group of dissidents, an already grim scenario of renewed repression turned still darker with the unexpected annoucement last week that Mstislav Rostropovich had been banished.

"Belgrade is over and this is a signal," said the wife of a man who had spent part of his life in Stalinist prison camps and now lives in Moscow. Signatories to the Helsinki agreement met recently in Belgrade to review the 1974 accord, including observance of its human rights provisions.

To this couple as to others, Rostropovich has been a special symbol. They knew that the world-famed National Symphony director and his wife, Galina Vishnevskaya, the soprano, had been abroad since 1974. Yet the notion that he could return here despite his occasional criticisms about restrictions on artistic freedom here and despite his long, protective friendship with author Alexander Solzhenitsyn, was comforting to the dissidents and human rights activists in their moments of depression.

This illusion was broken Thursday when the Supreme Soviet harshly denounced the famed cellist and his wife as "ideological degenerats" and stripped them of their citizenship. For the dissidents, it was one more in a series of unexpected blows to those who have dedicated themselves to criticizing what they see as Kremlin's failure to obey its own laws.

"Rostropovich was on a musical level with Solzhenitsyn," said the woman, "but he was not the same kind of dissident as Solzhenitsyn. This means that something serious is going on. When Rostropovich was in favor in Washington, the Soviets flirted with him, asking him to national receptions. Dobrynin [Soviet Ambassador Anatoliy F. Dobrynin] talked with him. "Cultivating Rostropovich improved the Soviet image in the United States, she said.

In typically Russian style, many dissidents and other nondissenting intellectuals in this capital spent many hours last week analyzing the move against Rostropovich for signs of the intentions of the leadership. Yet, only the Kremlin really knows and this is as much a part of the psychological warfare waged against the dissidents as many of the overt acts.

The searchers find much that is disturbing in recent days.March has seen these things happen so far: banishment of Pyotr Grigornko, the old Red Army major general who has had his citizenship stripped from him while in America for medical treatment; the banishment of Rostropovich and Vishnevskaya; an attack on Yuri Lyubimov, the innovative director of the famed Taganka theater, and Kremlin boasting about its success at the Belgrade conference where the United States was thwarted in efforts to raise substantive questions about Soviet violations of human rights.

In addition, the dissident community has been jarred by the reports from Washington that a dissident turncoat who has denounced the movement, tral Intelligence Agency 1975-76. Lipavsky was the author of a denunciation of Anatoly Schransky, a dissident who has been arrested and charged with treason in a case that continues to be an international cause celbre.

In the minds of many, the action against Rostropovich's is especially alarming because the Kremlin had gone to great lengths to cater to the musician, allowing him unusual freedom to work abroad. For a number of years, the leadership seemed satisfied if he simply came home from time to time to demostrate his loyalty.

"They wanted to keep him as a Soviet who occasionally worked abroad," said one source. "But he made clear that he wanted conditions of freedom for himself and other illustrious musicians and that presented a choice of either changing the atmosphere in the country or forcing Rostropovich out. Of course, it was a lot easier to cut him off than to change the atmosphere."

At one point during his recent years away, the cellist was quoted as saying he would return here only if full artistic freedom was extended to him and other artists. He had the kind of special privileges that the leadership can extend to elite contributors to Soviet life. Rostropovich enjoyed a handsomely furnished country house and special practice facilities.

"As with other favored members of the intelligentsia, they wanted to create special privileges that the leadership source said. He said this is done from time to time with top scientists, "to give the impression that all scientists can freely come and go. But Restropovich decided not to participate in that compromise. This, plus his contracts with dissidents, was enought to convince them not to let him back."

The conductor had befriended Solhenitsyn when the author was being pilloried in the Soviet press in 1970 after he was awarded the Nobel Prize for Literature. Rostropovich spoke out for Solzhenitsyn. "This was never forgotten," said a source, a man seasoned by years of experience within the Communist Party. He spelled out the punitive ingredients in the decision against Rostropovich.

"They obviously wanted to punish him by separating him from his friends. He had relatives here, many friends, a house. As they see it, in the West he has only his music."

"In addition, it shows other musicians that they'd better stick to a pretty straight line, even a special person like Rostropovich can run afoul of authorities who are other wise eager to make exceptions."

In the view of this source, Rostropovich was a marked man ever his since defense of Solhenitsyn. "After that, Rostropovich's conditions of work deterioated here," he said.

A party member speculated that Rostropovich's recordings would never beseen again in state music stores.

"That's over," he said with a rueful shake of his head.

Sanya Lipavsky, worked for the [TEXT OMITTED FROM SOURCE]