The former U.S. ambassador to a series of secret meetings with the Russians said yesterday that, despite continuing allegations in some quarters that Moscow has violated nuclear arms agreements, the special commission examining such charges "has never yet had to deal with a case of real . . . and substantial non-compliance with an existing agreement."

Ambassador Robert W. Buchheim, who served as U.S. commissioner to the U.S.-Soviet Standing Consultative COMMISSION (SCC) from 1977 to early this year, told reporters that no clear-cut cases of cheating had been uncovered and that the commission had been successful in getting questionable activity either explained or stopped before it became a serious problem.

Buchheim's comments are significant because they come at a time when the Reagan administration is making its own review of various allegations of Soviet cheating on agreements, including the 1972 Strategic Arms Limitation (SALT I) agreement and another limiting anti-ballistic missile (ABM) defenses. The review is meant to help the new administration decide whether to confront the Soviets on this material again at the next meeting of the SCC in May in Geneva.

A list of several dozen alleged violations, some going back many years, has been put together within the U.S. Arms Control and Disarmament Agency under an ACDA deputy, David S. Sullivan, who is known for very hard-line views about the Soviet Union.Sullivan, who was forced to resign from the CIA in 1978 after supplying classified documents to a senator's aide, was involved in controversy again as a member of the Reagan transition team. Now the controversy surrounding him also attaches to the report and the question of how much of it should be presented at Geneva, administration sources say.

Buchheim, questioned by reporters at a luncheon of the Arms Control Association, said that while there may be some differences, he thought the current version of the ACDA report was basically a summary of all the compliance-related questions ever raised in the SCC. The commission has been meeting twice a year since May, 1973. Buchheim said it is "clear in my mind" that there is "nothing to re-examine" but it is "not unreasonable" for a new administration to want to look over it.

The ambassador provided a rare glimpse into the workings of the SCC. The United States, he said, has many times raised questions about Soviet missile and radar activity and Moscow probably never could be sure how much the U.S. intelligence really knew.

Sometimes, he said, the Soviets acknowledged an activity but said we had misinterpreted it. Some of this was true, he said; at times the United States recognized that its judgments had been flawed. Some of the Soviet response was probably not true and it was impossible to determine the reliability of some Soviet explanations, Buchheim said.

But whenever the United States was concerned enough to press for an agreement that the Soviets would not do certain things anymore, "it always has worked," Buchheim said.

Buchheim said that the list of alleged violations could have been made into a list of real violations if left "until we had a clear-cut case." But he said the purpose of the SCC was to head off the kind of trouble that could threaten an agreement if not addressed.

Unless the idea is to destroy rather than sustain an agreement, he said, "lying in the grass and . . . eventually jumping up and shouting 'gotcha'" is a "foolish" approach. He said he agreed with his predecessor, Sidney Graybeal, that it was most unlikely for the Soviets to sign an agreement that they would have to violate in order to do what they wanted.