A former Carter Administration official last night said the United States' policy toward the United Nations has undermined the international body's role as an effective arbiter of strife around the globe.

Charles W. Maynes, a former assistant secretary of state under Carter, discussed the U.S.'s "ambiguous" and counterproductive policies toward the international organization as part of the opening ceremonies of the Harvard Model United Nations conference in Boston.

"Everyone knows that the U.N. is in trouble," said the editor of Foreign Policy magazine. He warned that the organization is in jeopardy from "right wing animosity" on one hand and "left wing guilt" from the other. Maynes said the U.S. took the wrong approach toward the U.N. during both the Carter and Reagan administrations.

The problem, according to Maynes, lies with the American "foreign policy elite," that sees the U.N. as comprised of Third World nations hostile to U.S. interests.

The superpowers won't allow the U.N. to keep its "eyes and ears in areas of conflict," he said. The U.S. and the Soviet Union "want to make the Secretary-General depend on them."

The most effective and realistic roles for the U.N. are those of "facilitator, observer, and whistle-blower," said Maynes, adding that "states don't like to lose face" in the international arena. The foreign policy expert said that since 1945 the U.N. has made substantial contributions in peacekeeping, human rights and economic development.

But he said the U.N.'s position as a neutral arbiter is in jeopardy, particularly in the Middle East and South Africa, where the international organization has taken strong political stances. "These two issues...are tearing the U.N. apart," said Maynes, transforming it into "judge, jury and executioner."

Maynes criticized the "blustering" and "boisterous" tack that the Reagan Administration has taken toward the U.N. He said that the percentage of votes in which the U.S. has sided with the majority has declined from 40 percent in the mid-1950s to less than 15 percent today.