Banished and disgraced, dissident physicist Andrei Sakharov now stands in jeopardy of losing his most prestigious title -- academician.

While political expulsion from the elite Soviet Academy of Sciences is without precedent in post-Stalin Russia, a number of veteran foreign observers here believe the Communist Part may attempt it in the months ahead as the logical conclusion of official efforts to supress and discredit the regime's most powerful critic.

But as with much else here, no hard and fast assertions are possible about the amount of Communist Party penetration of the ruling structure of the academy, which generally has enjoyed a degree of independence from political control unknown elsewhere in Soviet society.

The academy's recent history shows both increased party influence and academy rejection of outside medling.

Ordinary Russians know little either of Sakharov's crucial secret work masterminding the Soviet hydrogen bomb program or of the fact that Soviet science has brought their otherwise underdeveloped industrial state strategic arms parity with the United States.

But based on the high prestige scientists have always held here, depriving Sakharov of the awesome title of akademik would have enormous symbolic importance internally.

Headquartered in a collection of Czarist-era, white-trimmed, yellow stucco buildings on broad Leninski Prospekt in Moscow, the academy theoretically sets general research directions for about 250 scientific institutions across the country where 40,000 researchers work.

As the sole voting members, its 240 or so individuals, most of them men and many of them not party members, stand near the pinnacle of Soviet society, enjoying privileges virtually unmatched outside the ruling Politburo. s

In addition to prestige, membership in the academy also has its practical side. Each academician receives a stipend equivalent to about $900 a month, as well as use of an academy car and other privileges.

Sakharov was admitted to this powerful group at the remarkably young age of 32 in recognition of his achievements in developing thermonuclear explosives ahead of the Americans. He subsequently secretly received the Stalin Prize, the Lenin Prize, and three times received the medal of a Hero of Socialist Labor, all of which were stripped from him on Jan. 22.

Ordered by the Supreme Soviet, the Russian figurehead parliament, and signed by Soviet President Leonid Brezhnev, that action was wholly political in nature. But last Monday the academy's own administrative head, the Presidium, censured Sakharov on the same grounds: for allegedly passing state military secrets to Western agents and defaming the motherland.

In the view of some here, that censure market direct manipulation by the party of the academy's handling of Sakharov, and may have set the stage for his eventual expulsion.

It is so far unknown here how this group of about 40 members reached their decision or whether it simply was directed from the party without a vote. But the censure's wording, as reported by the official Tass press agency, is very close to the phrasing of Article 35 of the academy's bylaws laying grounds for expulsion for "activities detrimental to our country. . . ." l

The last well-known censure move was in 1965 against T. D. Lysenko, the agronomist whose bogus claims of plant mutation, based upon data widely known to have been falsified, disrupted Soviet genetics for more than two decades under Stalin and Khrushchev.

But even Lysenko was allowed to remain an academician and some of his associates were accepted for membership months after his patron, Khrushchev, was ousted from power in October 1964.

During the Brezhnev era, the academy has shown contradictory signs of both yielding to what is thought of as remorseless party pressure for control and also rejecting it. In 1975, Mstislav Keldysh abruptly resigned after 14 years as academy president and was succeeded by Anatoly Alexandrov, a physicist.

As head of the famed Kurchatov Nuclear Institute, Alexandrov, then 72, had the requisite intellectual qualifications.

But the ambiguity that surrounds the academy and the party was underlined when Mikhail Suslov, Stalinist-era Politburo hardliner, showed up at the institution's general membership meeting to offer Alexandrov as the sole candidate for president.

Suslov's appearance was interpreted by Soviet scientists and Westerners alike as a signal the party intended to leave no doubt of its interest and role in controlling the academy.

Suslov told the academy it must play "an active part in meeting the tasks of communist construction." The same year, Brezhnev himself asserted that "our scientists subordinate their entire practical activity to the task of translating into reality the lofty ideals of communism. . . ."

Alexandrov in 1973 refused to sign a collective letter from other academicians calling on Sakharov to cease his political activity. The campaign against the dissident had reached bitter heights before Philip Handler, president of the U.S. National Academy of Sciences, sternly warned that Soviet-American scientific exchanges would be ended if the human rights activist were not left alone.

But again, the ambiguity: In October 1975, just before he was named academy president, Alexandrov joined 71 other academicians in condemning the awarding of the Nobel Peace Prize that year to Sakharov.

Although Sakharov's exile and loss of titles closely followed President Carter's interruption of Soviet-American science exchanges in reprisal for the Soviet invasion of Afghanistan, the party and the academy hierarchy clearly must be aware of the impact of expelling Sakharov on any future resumption of exchanges.

A two-thirds majority of the academicians, voting ostensibly in secret, is required either to accept a new member for life tenure or expel an old one. The next general meeting of the academy is expected in a few months. The Communist Party may already be canvassing for votes.