China and the Soviet Union indicated yesterday that they were taking opposite sides in the violent dispute between Vietnam and Cambodia.

In Moscow, the government newspaper Izvestia printed only the Vietnamese version of the quarrel with its fellow Communist state.

It was the first time that the Soviet media and taken notice of the dispute since Cambodia, accusing the Vietnamese of invading its territory, announced that it was breaking off relations with Hanoi.

In the account printed by Izvestia, Cambodia was accused of whipping up a campaign of "nationalist hatred" and "slander" against Vietnam. Izvestia noted that Vietnam had called for negotiations with Phnom Penh over rival territorial claims.

Hanoi kept up its propaganda campaign against Cambodia yesterday with the official newspaper Nhan Dan repeating changes of frequent attacks by Cambodian troops across the border.

As in other Vietnamese accounts, the dispute was described by Nhan Dan as involving disagreements over their common frontier. Cambodia, however, has accused the Vietnamese of trying to submerge it into an Indochinese federation dominated by Hanoi.

Meanwhile, reports attributed to travelers in Vietnam said the fighting with Cambodia "is continuing in the Hatien-Tayninh boundary area consisting of air raids launched from Saigon into the Parrot's Beak area [of Cambodia] and artillery exchanges."

China, on the other hand, printed only brief extracts from Vietnam's account of the dispute, omitting all of Hanoi's more virulent accusations about alleged Cambodian atrocities. The printed material did include Hanoi's call for talks, however.

By contrast, Chinese media carried virtually complete versions of Cambodia's charges against Vietnam. Also included was Phnom Penhis "warning" to the "foreigners" it said were serving as commanders and advisors to the invading Vietnamese forces.

While Cambodian diplomats have refused to specify the nationality of the "foreigners," it is believed Phnom Penh is trying to link the Soviet Union with the alleged offensive by Vietnam.

For several months, Peking has been trying to get Cambodia and Vietnam to settle the situation along their border. Since the Communist' victories in both countries in April 1975 the conflict has escalated from small skirmishes to what appear to be division-size battles.

China's role as a mediator has been complicated, however, by its own strained relations with Hanoi. China has been antagonized by the emphasis the Vietnamese have placed on their links with the Soviet Union.

China has been Cambodia's only significant ally since the Communists came to power there. The Soviet Union is in disfavor in Phnom Penh because of its close ties with Vietnam and because it failed to support the Cambodian Communists during the fighting.

The reports from travelers, which were circulating in Hong Kong, said that "ground fighting involving tanks left behind in southern Vietnam by the Americans has stalled."