President Carter, in an interivew broadcast last night, said the Soviet Union may have stalled completion of a strategic arms limitation treaty (SALT) at Geneva last month because of concern about U.S.-China ties.

"That was an impression we got," Carter said to NBC correspondent John Chancellor, noting that, despite public and official denials by Moscow, "I think there was possibly some interrelationship in the Soviets' minds about this."

When he announced on Dec. 15 that the United States was normalizing its relations with China, which is Moscow's arch-rival, Carter said he did not believe the action would have "any adverse effect at all" on the SALT negotiations. Some high White House officials were quoted at the time as saying they believed the China ties would even enhance the completion of a SALT pact.

Several administration officials involved in the SALT process have expressed the belief that Soviet negotiating instructions were changed during the course of Foreign Minister Andrei A. Gromyko's Dec. 21-23 meetings at Geneva with Secretary of State Cyrus R. Vance. The officials have speculated, as Carter did publicly in the NBC interview, that China policy was at the heart of the last-minute negotiating difficulties.

Carter also told NBC that the Soviets may have wished to put off a SALT signing coremony and visit here by President Leonid I. Brezhnev so it would not be so close in time to the U.S. trip of Chinese Vice Premier Teng Hsaio-ping, who is due in Washington Jan. 29.

Carter said the Soviets earlier had suggested mid-January for the Brezhnev summit, although Soviet sources maintain that this was Washington's idea rather than theirs.

"We have almost concluded the SALT negotiations," Carter said in the interview, which was taped Saturday. "There are some minor but important issues to be agreed. We are working on it. And my hope is that they will be concluded without undue delay."

U.S. officials reported that the major issues have been resolved in diplomatic exchanges following the Geneva meeting. The minor problems which remain could be resolved at almost any time the leaders in Moscow wish to complete the deal, officials here said.

A common guess among American policymakers is that Moscow will wait until after the Teng visit to complete the final details on the SALT treaty. By so doing, the Soviets would be able to look over Washington's shoulder as the ties with China are cemented and celebrated, and have a quick means of expressing their conclusions.

In an interview with Time magazine, Brezhnev renewed his commitment to signing of a new treaty limiting nuclear aresenals "in the near future." The United States has been told that the SALT pact and the Brezhnev summit does not hinge on the Teng visit, although Moscow has also made it plain that U.S.-Soviet relations in the future hinge to some degree on the nature of Washington's relations with Peking.

In response to Chancellor's statement that the Soviets were "terribly gleeful" about Vietnam's invasion of Cambodia and that the Soviets "are up to various kinds of mischief around the world," Carter said Soviet activities in the "Third World are among the obstacles to "a more complete relationship of detente."

Carter said he believed that the Soviets encouraged the Vietnamese to invade Cambodia, and that they encouraged the dispatch of Cuban forces to various parts of Africa. This is "disturbing to us," he said.