President Carter told United Nations Secretary-General Kurt Waldheim yesterday he is interested in addressing the United Nations, but when and on what subject remain undisclosed.

Waldheim informed reporters of the President's interest at a news conference after the two men spent more than an hour discussing what was described as a "full range of economic, social and human rights issues." including Cyprus, the Middle East, Southern Africa and the plight of Americans in Uganda.

There have been unconfirmed reports that Carter may visit the United Nations to make a major policy statement on Africa, perhaps next month when the U.S. ambassador, andrew Young, is sitting as chairman of the Security Council.

"The President did indicate his interest to come to the United Nations to address the U.N., but it has not been decided yet when and in what form," Waldheim said.

"I can assure you that President Carter repeatedly stressed the need for close cooperation with the United Nations," he said. "It is my firm impression that the President wants to use this instrument of peace . . . in a more effective way, and I'm very glad about this."

Press secretary Jody Powell announced four subcabinet appointments yesterday and said the President ordered a government-wide review of 1,156 federal advisory committees.

". . . Many existing committees have outlived their usefulness, or are not providing truly balanced advice and recommendations," Carter said in a [WORD ILLEGIBLE] he heads of all departments [WORD ILLEGIBLE] ncies.

The [WORD ILLEGIBLE] said 947 committees not [WORD ILLEGIBLE] by law should be abolished unless they serve a "compelling need," have "truly balanced membership," and "conduct their business as openly as possible consistent with the law and their mandate. . . ."

All told, the 1,156 committees cost $538 million a year, Powell said.

Appointed to the administration were:

John M. Sullivan, assistant secretary of defense for manpower and reserve affairs. Sullivan, who owns a small business, was coordinator of the Carter primary election campaign in Pennsylvania and a Carter delegate to the Democratic National Convention.

David E. McGiffert, assistant secretary of defense for international security affairs. A partner in the law firm of Covington and Burling, McGiffert contributed position papers to the Carter transition team.

Gerald P. Dinneen, assistant secretary of defense. He is director of the Massachusetts Institute of Technology lincoln Laboratory.