MOSCOW, AUG. 9 -- The Soviet Union today condemned Iraq's annexation of Kuwait and left open the possibility of taking part in a multinational military action in the Persian Gulf region under the leadership of the United Nations.

Asked by reporters if the Soviet armed forces could take part in any future clash with Iraq, Foreign Ministry spokesman Yuri Gremitskikh said, "The Soviet Union stands for coordinated actions within the Security Council of the United Nations. If this organization takes a decision on the use of a multinational force, the Soviet Union will on this basis work out the line to be followed."

"At this time," Grimitskikh continued, "there is no question of taking part in a multinational force or sea blockade outside the realm of the U.N. Security Council."

The Soviet Union's decision to condemn a longtime ally in the Middle East and to support international pressure on Iraq after the invasion is the clearest example since the withdrawal of troops from Afghanistan that Kremlin leader Mikhail Gorbachev has adopted a wholly new course, known here as "the new thinking," in foreign policy.

The Soviet Union has about 8,000 Soviet citizens in Iraq, including 1,000 military advisers, and has supplied arms to Baghdad for three decades. Soviet sources say that Iraq owes the Soviet Union more than $20 billion.

Although the ranks of the Soviet Foreign Ministry are filled with officials who are considered longtime supporters of the Iraqi government, Gorbachev and Foreign Minister Eduard Shevardnadze clearly have decided that Moscow will not stand by Iraqi President Saddam Hussein during the crisis.

A Foreign Ministry spokesman said that Gorbachev, who is on vacation in the Crimea, has sent two "communications" to Saddam criticizing the invasion and has received only "negative" replies.

A Foreign Ministry statement expressed disappointment with Gorbachev's failure to sway Saddam. "We thought this exchange of views with the Iraqi side gave rise to hopes that matters would go towards the implementation of Resolution 660 of the Security Council and thereby quickly defuse the crisis," the statement said.

"Unfortunately we are obliged to recognize that our hopes have not been justified. Iraq has not only failed to withdraw its forces from Kuwait but also yesterday declared what adds up to annexation of the country. We cannot remain silent, and we cannot tell lies."

Gremitskikh read a statement that did not criticize President Bush for deploying thousands of troops and warplanes to Saudi Arabia, but did express concern about the possibility of general military escalation in the Persian Gulf region.

"The tendency towards the escalation of confrontation and the building up of passions is unfortunately gaining strength," the statement said. "Such a course of events generates concern and worry in Moscow, inasmuch as it is occurring in a region where there is already a surfeit of 'explosive material.' "

Asked if Moscow condemned Bush's military moves in the region, Gremitskikh said that the government "took note of the assurances from the American secretary of state that the deployment of American troops in Saudi Arabia is a temporary and extraordinary measure."

In an unprecedented show of post-Cold War cooperation, Shevardnadze and Secretary of State James A. Baker III issued a joint statement here last week condemning the Iraqi invasion.

While the Soviet official media responded to U.S. military actions in Grenada and Panama with accusations of "gunboat diplomacy," the newspapers and television broadcasts this time have saved their criticism for Saddam. The Bush administration's deployment of forces was reported on the evening news tonight only as a matter of fact.

Although the Soviet Union could stand to lose a great deal of money by turning against Saddam -- the Iraqi press has already villified Gorbachev's position -- Western diplomats here say that its show of good faith is likely to win it credit in the West. On Wednesday, Bush called the Soviet reaction to the Persian Gulf crisis "responsible."