MOSCOW -- Andrei Sakharov is not given to formalities, but this night is different. He is sporting a pinstriped suit and a new tie, and as the evening wears on, he rises to speak, bringing silence across the dinner table.

As snow falls and the cold winds blow outside, Sakharov exudes a rare warmth, laughing out loud at the odd Art Buchwald joke, bolstered by the feast of suckling pig and Georgian wine.

Surrounding him are two dozen of the world's leading human rights activists. Some flew in from as far away as New York, surprised to receive visas. Others, including a handful released last year from Soviet prisons, came by bus from across Moscow.

If the mood, fare and company are vintage, so are the guest of honor and his feat. Devoted to scientific research, committed to human rights activism, Sakharov stayed the course of both, forging an independence unparalleled in a country firmly ruled by one hard-knuckled Communist Party.

Two decades ago, at age 46, Sakharov abruptly broke ranks from his career as a high-ranking physicist in the Soviet Academy of Sciences, choosing instead to protest the treatment of the nation's downtrodden, particularly those wrongly accused and falsely jailed. Eventually he took a stance against such official Kremlin acts as the 1979 invasion of Afghanistan.

Harassed by the KGB, jeered by his peers in Soviet officialdom, he was banished for seven years to the closed city of Gorki, out of the reach of western journalists and diplomats in Moscow. Many surrounding Sakharov on this night had suffered in his grief and their own.

Naum Meiman, at 76 the oldest human rights warrior in Moscow, had fought bitterly for his wife to receive cancer treatment in the West, only to have her die a year ago, days after reaching the United States.

Larisa Bogoraz had received a visit from KGB agents in November 1986, forcing her to sign emigration papers for herself and her husband, activist Anatoly Marchenko. Days later, she learned that he had already died in prison of unknown causes. "It used to be that we had vodka at such feasts to give us a bitter taste," she told the gathering, "and now, instead of vodka, you can have a few words from me."

For Sakharov, the years of exile had been brutal. When he was back in Moscow, old friends found him changed utterly. Ill and shaken, he declared his intention to return to a career in science.

After retreating to near-seclusion in his central Moscow apartment with his wife, Yelena Bonner, Sakharov, now 66, faced criticism for withdrawing from the everyday struggle against Soviet human rights abuses. "When I called up Sakharov, he hung up," one would-be emigre said. "He said he could not help me."

And yet, since returning, Sakharov has adopted a moderate political stance and clung to his independence, sometimes supporting western positions, sometimes criticizing them. In November, for instance, he told western journalists that a major Gorbachev speech was "simply too soft." In an interview with the official news agency Tass a month later, he praised Soviet arms control positions on the eve of the Washington summit.

More important, Sakharov has adopted two causes as his own: an end to Soviet involvement in Afghanistan and the release of all Soviets imprisoned for criticizing Communist Party actions or for other political reasons. Using his access to Soviet officials, Sakharov has spent the year waging a quiet campaign for both.

Twice he got the ear of Mikhail Gorbachev and twice he implored the Soviet leader to grant an amnesty to the "prisoners of conscience" in jails and camps across the Soviet Union. When he met with Gorbachev last month, he handed over a list of the 200 political prisoners to be set free.

Since Sakharov's return to Moscow from Gorki in December 1986, opportunities for emigration from the Soviet Union have increased. About 200 Soviets imprisoned for political acts have been released, including Lev Timofeyev and Sergei Grigoryants, both guests at this dinner.

As Sakharov pauses for breath, preparing to offer his own advice, he looks around the table. Unlike Alexander Solzhenitsyn, Anatoly Shcharansky and other well-known Soviet activists of the recent past, who either chose to leave for the West or were forced to emigrate, most of tonight's guests have decided to stay.

Theirs is a special burden. Timofeyev, a writer who was imprisoned in 1985 for works critical of the Soviet economy, has founded the Press Club Glasnost, an organization for monitoring human rights abuses in the Soviet Union. In the 1970s and early 1980s, Soviets were jailed for such activities.

Grigoryants, also jailed for distributing critical works about Soviet human rights, began publishing the magazine Glasnost soon after his release last February. He has been attacked in the official Soviet media and harassed by security agents but still allowed to continue.

In closing a dinner of remininiscing on a crisp January night, Sakharov urges the table guests to join the fight for bringing the Soviet troops home from Afghanistan and for freeing the remainder of Soviet political prisoners.

"Up until now," Sakharov says as he rises to take the floor, "the situation was very difficult, but it was a clear one. It was clear that there were problems with human rights, and it was clear that there were problems with peace. That put a very heavy pressure for those of us who are here at the table.

"Now I would say that the situation has become more complex. It has become more complex because it has become better."