he emigre literary elite of the Soviet Union gathered at the New York Public Library for a few rare hours tonight to mark the freedom--and pain--of life in forced exile from their homeland.

Officially called "The Third Moscow Book Fair Reception in Exile," the evening brought together virtually every major Soviet writer who has emigrated or been expelled from Russia in the past decade. These writers dared to challenge the Communist Party's vise grip on free expression inside the U.S.S.R. by having their books published abroad or by agitating for greater human freedoms at home.

About three dozen former Soviet citizens, most of whom now live in the United States, and more than 150 others, including the U.S. publishers who print their works and media and human rights advocates, found themselves deep in a wonderfully Russian evening. There were rounds of food and drink, intense conversation, gossip, disagreements, lobbying and reminiscences of a life that has closed down for good for the principal guests.

Sponsored by the Association of American Publishers and the Fund for Free Expression, the evening was a reunion of people who, despite sometimes bitter differences among themselves, have become bonded together out of a resolve to speak their minds.

The guests represented the spectrum of Soviet intellectual dissent that has taken root in the motherland in the face of tighter and tighter oppression by the secret police and the party. They ranged from the earliest emigre's of the 1970s, like Andrei Sinyavsky, who left the U.S.S.R. after being imprisoned in the mid-1960s for anonymous works published in the West, to Vladimir Voinovich, who was forced into exile in Munich last year after years of confrontation with official censors. The only conspicuous absence was that of Alexander Solzhenitsyn, now living in Vermont, who was invited but who did not attend.

To a person, the writers are in painful transition to find their voices and their art again in lives transported from the intensity of repressed intellectuals in Moscow and Leningrad to the seemingly wide-open and confusing multitude of voices and freedoms in the West.

Lev Kopelev, white-bearded patriarch of the most important and influential literary salon in Moscow, where for more than 10 years he offered succor, advice and assistance to dozens of writers and human rights dissidents, put his fate this way in a tribute to other Soviet activists now arrested or banished within their own country:

". . . books are as necessary for some people as bread. For us, the word is also our weapon in resisting brutal tyranny; we cannot decide the problems of armament and big politics, but we can defend peace by working for human rights. Our freedom in speaking and publishing which we now enjoy is also our duty."

Kopelev arrived in the United States only Friday after more than a year as an honored emigre' in West Germany. There he is famous for his scholarship in German literature and for his ringing defense of close friend Andrei Sakharov, the Nobel Peace Prize laureate and father of the Soviet hydrogen bomb whom the party sought to silence in exile in Gorky, outside Moscow, last year.

After his brief remarks, Kopelev gathered with other close friends like Dusia Kaminskaya, a dissident lawyer, and former Soviet army Maj. Gen. Pyotr Grigorenko, who was imprisoned in psychiatric hospitals for more than five years in the early 1970s and became a founding member of unofficial citizens' groups to monitor Soviet compliance with human rights guarantees of the 1975 Helsinki accords.

Vasili Aksyonov, a preeminent writer of the Khrushchev thaw of the 1960s who was forced into exile last year with his wife and family, and now is a fellow of the Smithsonian Institution's George F. Kennan Institute, told the gathering that "the Moscow apparatchiks claim that by sending writers into exile they are purifying the air of our country. This, of course, is not true: They are not purifying the air, but replacing it. I would say they are creating a new, oxygen-less civilization."

The idea for the reception for exiled writers came from Robert L. Bernstein, chairman of both Random House and the Fund for Free Expression, as a kind of counter-event to coincide with the Third Moscow International Book Fair, which took place in the Soviet capital earlier this month. Bernstein said he thought of the reception as a way to "send a message" to Soviet authorities, whose two previous book fairs in 1977 and 1979, hailed by the official Soviet press as examples of Soviet acceptance by Western publishers, were marked by censorship battles with American and other publishers over a variety of books by Soviet dissidents and Western writers the foreigners sought to exhibit.

American attendance at this month's Book Fair in Moscow was cut drastically by a combination of poor profits from previous fairs, the Soviet invasion of Afghanistan and the exile of Sakharov, according to Geri Laber of the Helsinki Watch Committee, which helped organize tonight's Reception in Exile. With few U.S. publishers in Moscow, the possibility was eliminated for holding what had become an extraordinary tradition -- a dinner sponsored by the Americans for their Soviet writers at a well-known Moscow restaurant.

Laber said Bernstein suggested about a month ago holding the reception here in New York, since many of the Soviets who had attended the Moscow dinner receptions had themselves been forced into exile in the intervening years.

In his remarks, Bernstein said that since the 1979 Moscow fair, "The Soviet government has sent an unmistakable message to the international world of books and ideas. It goes like this: We will exile our writers whenever we wish . . . Our writers will conform to a single unwritten command and it is this: You will not criticize or appear to criticize the Soviet state or the people who run it . . ."

Or, as Voinovich put it tonight, "Needless to say, in our books Soviet reality does not look very appetizing. It has too many prisons, labor camps, interrogators and guard dogs. It has sobering-up stations, madhouses, squabbles in communal kitchens and lines for potatoes. But the people responsible for this aren't writers but those who built this existence and who want it to stay that way forever."