ABU DHABI, UNITED ARAB EMIRATES -- A series of high-level contacts between the conservative and staunchly anticommunist rulers of Saudi Arabia and the Soviet Union have put the oil-rich kingdom on a path to establishing formal diplomatic relations with Moscow, according to Arab and western diplomats in the region.

The prize of a diplomatic breakthrough with Saudi Arabia's influential ruling family has been a long-sought goal of the new Soviet leadership under Mikhail Gorbachev, whose Middle Eastern envoys have combined Moscow's "new thinking" on Middle East policy with an energetic brand of diplomacy to advance Soviet influence in the region over the past two years.

Western officials, closely following the dialogue between the two countries, say it appears that many of the barriers to a formal relationship between Moscow and Riyadh have been removed. But they caution that the Saudis still want to see constructive Soviet participation in solving difficult regional problems such as the Iran-Iraq war and the Arab-Israeli dispute before taking the final step toward formal diplomatic ties.

"There are a lot of IOU's out there," said a western official in Riyadh, "and until some of those IOU's are paid up, I wouldn't hold my breath."

But senior-level contacts between the two governments are on the increase.

In the past year, Saudi Arabia for the first time sent its oil minister, Hisham Nazer, to Moscow seeking cooperation on oil pricing policy. Earlier, the son of the kingdom's ruling monarch, King Fahd, led a sports delegation to the Soviet capital. And last month, Saudi Foreign Minister Saud Faisel and Saudi Ambassador to Washington Prince Bandar bin Sultan met with Soviet leaders to press the views of gulf Arab states on the need to impose sanctions against Iran for failing to comply with a United Nations cease-fire vote in the seven-year-old Iran-Iraq war.

The foreign minister's trip to Moscow was followed this week by the arrival in Riyadh of Vladimir Polyakov, director of the Middle East desk in the Soviet Foreign Ministry.

Polyakov's visit to Riyadh represents the first high-level visit by a Soviet official to Saudi Arabia in 53 years, according to western officials.

"It doesn't make any sense for the Saudis not to have relations with the Soviet Union," said an Arab official here. "It is now only a question of time."

King Fahd already has "accepted the idea" of establishing diplomatic relations with the Soviets, according to a knowledgeable official here. He added that such an idea would have been treated as "heresy" by the Saudis as recently as a decade ago.

Kuwait was the first gulf state to establish ties with Moscow in the early 1960s. In recent years, both Oman and the United Arab Emirates have followed suit. One official here said that an initial UAE attempt to establish relations with Moscow in 1974 was blocked by the Saudis. Among the remaining gulf Arab states, Bahrain and Qatar are likely to defer any decision on Soviet ties until the Saudis make a move, Arab diplomats said.

One knowledgeable source familiar with attitudes in Saudi Arabia's ruling family said that the kingdom's more frequent contacts with Soviet officials are an extension of growing Saudi involvement in regional and international affairs. This source cautioned, however, that King Fahd has adopted "a wait and see" posture until he "sees how the Soviets perform."

In addition, there remains a basic suspicion that Soviet arms supply relationships with North and South Yemen, Ethiopia, Syria and Iraq may yet represent a long-term threat to Saudi security and overall stability in the region, according to this source.

Diplomatic sources in the region said the key to the timing of such a move depends on Soviet performance in playing a constructive role on these issues of vital importance to the Saudis:

The withdrawal of Soviet forces from Afghanistan, where Saudi Arabia has helped finance, along with China and the United States, the mujaheddin resistance movement.

Soviet support for an arms embargo against Iran for not complying with a United Nations cease-fire resolution in the Iran-Iraq war.

Continued Soviet sponsorship for an international peace conference to mediate the Arab-Israeli dispute and find a solution for the future of Palestinian Arabs living in the Israeli-occupied West Bank and Gaza strip.

Some Arab officials believe the increased dialogue between Riyadh and Moscow stems from a Saudi determination to "balance" its relations between the two superpowers after a string of disappointments over scuttled American arms sales and aborted Middle East peace initiatives.

Aside from its naval deployment to the Persian Gulf, U.S. policy on the Arab-Israeli dispute continues to frustrate Arab leaders who want Washington to pressure Israel to accept the idea of an international Middle East peace conference.

One official here said it has become imperative for the Arab states to consult with the Soviet Union because the Soviets have relations with Iran while the Americans do not.

Moreover, the Soviets have been more active than the United States in building support for an international conference, which is supported by a majority of Arab states.