The U.N. General Assembly voted tonight to continue to seat representatives of the ousted regime of Pol Pot as the delegates from Cambodia in a defeat for the Soviet Union and Vietnam.

The Cambodian issue splits the nonaligned movement and is a major point of confrontation between China and the Soviet Union, but the General Assembly vote indicated that the principle of condemning foreign invasions is important to more nations than the reality of who controls a government.

Pol Pot's forces are fighting a guerrilla war against the Phnom Penh government of Heng Samrin that was installed by Vietnam after Vietnamese troops overthrew Pol Pot in January.

The 71-to-35 vote with 34 nations abstaining and 12 absent was a victory for China, Pol Pot's strongest supporter, and for the noncommunist ASEAN states of Southeast Asia that are alarmed by spreading Vietnamese military control in Indochina. Vietnam dominates Laos as well as Cambodia.

It was also a vote replete with contradictions as several of the speakers in the 6 1/2-hour debate noted.

Nations like the United States that have condemned Pol Pot's regime since its 1975 beginning for its brutal abuses of its people voted for his delegates.

Vietnam and Eastern European nations that ignored reports of human rights abuses in Cambodia for years now cite them as justification for Pol Pot's overthrow.

Singapore Ambassador Tommy Koh made the major speech supporting the Pol Pot case. He rejected arguments that the regime's brutality justified a foreign invasion.

"If we were to accept a doctrine of humanitarian intervention I submit the world would be an ever more dangerous one than it is now for smaller states," he said.

Vietnam and the Soviet Union realized before today's debate began that they could not win an outright victory replacing Pol Pot's delegates with Heng Samrin's.

They pushed instead to win approval of a compromise proposal that would have left Cambodia's seat vacant.

The compromise, introduced by Indian Ambassador S. N. Mishra, was described by Vietnam's Ambassador Ha Van Lau as "the nonaligned resolution," and Mishra said it stemmed from the "empty seat" compromise accepted by the nonaligned nations' meeting in Havana earlier this month.

However, Yugoslavia, Senegal, Singapore and other members of the nonaligned movement opposed the compromise and demonstrated by their speeches that the movement remains sharply divided after the frictions of Havana.

Koh alluded to the "empty seat" arrangement reached in Havana but said he would not discuss how it was arrived at in detail because "as a nonaligned member I do not think we should wash our dirty linen in public."

Koh appealed to the African and Arab groups of states to listen to the ASEAN nations on the Cambodian question since it is an Asian matter.

He also reminded "my Arab friends" that they have long championed the principle of not recognizing occupation of territory conquered by force in denouncing Israel's territorial acquisitions in the 1967 Middle East war. He asked them to be consistent.

Koh said that those seeking to change Cambodia's representations here had "put their friendship with Vietnam above principle."

"If, instead of Vietnam, Thailand had on Dec. 25,1978, sent in 10 divisions and overthrown Pol Pot," Koh asked Vietnam's friends, "would you today take the same position?"

U.S. Ambassador Richard Petree and other speakers stressed that their support for the Pol Pot delegates did not mean they condoned the Pol Pot dictatorship's atrocities. Petree added that Heng Samrin's government is also worthy of condemnation for endangering Cambodia's people with famine and putting obstacles in the way of international food aid.

In addition, Petree said, "At this moment [the Vietnamese] invasion forces have embarked on a new offensive which can only increase the suffering of the Cambodian people."

In a forceful plea for the "empty seat" compromise, Mishra accused Pol Pot's backers of illogic when they insist that their votes do not condone his human rights abuses while maintaining that a vote to oust his delegates was a vote approving foreign invasion.