As at least three Warsaw Pact nations inch closer toward restoring some diplomatic links with Israel, the Soviet Union appears to be searching for a way to redefine its relationship with the Jewish state in order to become a player in the arena of Middle East peace negotiations.

That is the assessment of senior Israeli foreign policy advisers here and of western diplomats in Moscow and Warsaw. However, many of the diplomats cautioned against expecting any early breakthrough either in a restoration of the Soviet-Israeli diplomatic ties, which were severed in 1967, or in any massive increase in Jewish emigration from the Soviet Union.

Still unconfirmed press reports here and in Europe of secret deals involving the imminent transfer of up to 20,000 Soviet Jews to Israel could be part of a Soviet campaign to defuse the emigration issue before the Geneva summit between President Reagan and Soviet leader Mikhail Gorbachev, Israeli officials here and diplomatic sources in Moscow said.

The Israeli officials insisted that there is no basis for optimism about a change in Soviet emigration policy and characterized reports of a pending Moscow-Tel Aviv airlift of Soviet Jews as "wishful thinking."

Less amorphous, however, have been diplomatic contacts suggesting that Eastern Bloc countries, with Soviet approval, are moving toward reestablishing low-level diplomatic relations with Israel.

Poland and Israel already have agreed to restore limited ties and soon will announce the opening of interests sections in Warsaw and Tel Aviv, according to government officials here and in Warsaw. Romania currently is the only Soviet Bloc country with full diplomatic relations with Israel.

Israeli Foreign Minister Yitzhak Shamir, who met at the United Nations last month with his counterparts from Poland, Hungary and Bulgaria, said last week that he had received signals from two Eastern European countries in addition to Poland that they, too, are interested in strengthening ties with Israel. While Shamir would not name the two countries, they are widely presumed here to be Hungary and Bulgaria.

However, an informed Israeli government source said, "We are not at a stage with any Eastern European country that is near to the point that we have with Poland." Eastern European sources in Moscow denied reports that Hungary -- believed to have the largest Jewish population in the Soviet Bloc outside the Soviet Union -- is considering restoring ties with Israel, Washington Post Moscow correspondent Celestine Bohlen reported.

Western diplomats in Warsaw said that Poland's renewal of ties with Israel may serve as a model for similar moves by Hungary and Bulgaria and that their capitals, Budapest and Sofia, could serve as connecting points for air service between the Soviet Union and Israel, Washington Post Warsaw correspondent Jackson Diehl reported.

The diplomats noted that unlike Romania, Poland, Hungary and Bulgaria are unswervingly loyal to the Soviet foreign policy line and could provide a more reliable link for Soviet-Israeli contacts.

In confirming Poland's intention to restore some ties with Israel, officials in Warsaw last week stressed their adherence to the Soviet policy of calling for Israeli withdrawal from all territory occupied in the 1967 Middle East war, the establishment of an independent Palestinian state and the convening of an international conference on Middle East peace that includes the Soviet Union.

In addition to the Soviet Bloc moves toward some diplomatic ties, there have been other signs of Soviet relaxation toward Israel.

The first was in July, when Israel's ambassador in Paris, Ovadia Sofer, and his Soviet counterpart, Yuli Vorontsov, met and reportedly discussed a renewal of ties and an increase in emigration of Soviet Jews. Last month, in a break with tradition, Sofer was invited to a Soviet reception in Paris during Gorbachev's visit to the French capital.

During the Paris visit, Gorbachev said at a press conference, "The sooner the Middle East situation is normalized, the sooner one can proceed with consideration of a normalization of relations" between Israel and the Soviet Union. Middle East diplomats in Moscow told Post correspondent Bohlen that they thought the Soviet leader's remark gave a hint of a new approach to Israel.

Moreover, unconfirmed reports that the Soviets may be ready to release dissidents Anatoly Scharansky and Andrei Sakharov and the reported issuance of an exit visa to Sakharov's wife, Yelena Bonner, have fueled speculation that the Kremlin is on the verge of relaxing relations with Israel. Diplomats here cautioned, however, that the reports could be the result of presummit maneuvering.

In a narrow context, Israeli officials and western diplomats in Moscow said, Moscow's tentative moves toward relaxing relations with Israel can be viewed as another indication of Gorbachev's apparent efforts to rid Soviet diplomacy of obstacles as it pursues high-priority economic objectives.

Renewal of ties between Israel and the Warsaw Pact states would give the Soviet Union and its financially strapped satellites enhanced access to financial sources in the West, analysts here said.

For example, the Polish government of Gen. Wojciech Jaruzelski, isolated by much of the West after the imposition of martial law in 1981, remains anxious to strengthen contacts outside Eastern Europe in the search for western technology to modernize Poland's economy. Like other Soviet Bloc countries, Poland views Israel as a potential source of economic exchange, according to western diplomats in Warsaw.

Bulgaria is the Soviet Union's closest ally in Europe and has played surrogate for Soviet foreign policy moves in the past. A Bulgarian connection to Israel would be the closest the Soviets could come to ties with Israel short of direct diplomatic relations, western diplomats in Warsaw told Diehl.

From a broader perspective, the Soviet Union's apparent overtures to Israel can be viewed as an attempt by the Kremlin to clear the way for a more active diplomatic role in the Middle East, according to Israeli officials and western and Middle East diplomats in Moscow.

In his speech to the U.N. General Assembly last month, Israeli Prime Minister Shimon Peres suggested that the Soviet Union could participate in an international forum to initiate Middle East peace talks if it reestablished diplomatic relations with Israel.

However, the usually well-informed Soviet journalist Victor Louis said that restoration of relations with Israel and Soviet participation in Middle East peace talks are viewed in the Kremlin as separate issues.

Noting that the Soviet Union was the first nation to recognize Israel in 1948, Louis told the London correspondent of the Hebrew daily Maariv in an interview that he would not rule out the possibility of a renewal of ties.

"But Mr. Peres must not present an ultimatum that if the Soviet Union does not restore relations it won't be allowed to take part in Middle East peace negotiations. This approach won't succeed. The relations have to develop by themselves in stages. The issues of the Middle East in general and Israel and the Soviet Jews, these are separate issues," Louis was quoted as saying.

Analysts here, noting unconfirmed reports that Egypt and Jordan had begun to urge the Soviet Union to restore ties with Israel in order to get an international conference on the Middle East going, said that Moscow would be confronted on the question by its strongest ally in the region -- Syria -- unless Syrian President Hafez Assad won assurances of significant Israeli territorial concessions on the Golan Heights, which Israel captured from Syria in 1967.