On the first day back from Easter recess, two influential members of the Senate Intelligence Committee put the Reagan administration on notice from the floor of the Senate that there is widespread concern that the CIA is circumventing a congressional ban on U.S. involvement in efforts to overthrow the Nicaraguan government.

Sen. Daniel Patrick Moynihan (D-N.Y.), vice chairman of the committee, said that in addition to its obligations under the congressional ban the United States has a "specific obligation" not to violate the 1948 Organization of American States treaty, which prohibits any OAS country from intervening in or interfering with the affairs of another OAS country.

"If we are a government of laws at home, it is hoped we would be a government of laws in the hemisphere," Moynihan said.

While Moynihan was speaking, the OAS permanent council was hearing charges by Nicaragua against the United States. The statements were made during a debate on a proposal by Honduras for a negotiated settlement of disputes in the region through a meeting of five Central American foreign ministers.

In the Senate, Patrick J. Leahy (D-Vt.) said he has given the Intelligence Committee a classified report that "bears materially" on whether the executive branch is complying with "both the letter and the spirit" of restrictions placed by Congress on secret operations in Nicaragua.

The restriction, known as the Boland amendment, prohibits the CIA or Defense Department from providing funds or other support to counterrevolutionary groups for the purpose of overthrowing the Nicaraguan government.

"If one is to believe the detailed accounts seen in the press in recent days, the administration is actively supporting, and perhaps even guiding, a large-scale anti-Sandinista guerrilla movement now involved in open combat inside Nicaragua," Leahy said.

Senate Majority Leader Howard H. Baker Jr. (R-Tenn.) said "there is a great concern" in the Senate about U.S. covert activities in the region. Baker met with Moynihan after the New York Democrat's remarks on the floor. Baker later said he would ask for a leadership briefing by the Intelligence Committee.

Moynihan said the committee has spent a quarter of its time in the past year on intelligence operations in Central America. He said Sen. Barry Goldwater (R-Ariz.), the chairman, has asked for a new briefing from administration officials next Tuesday. One of Goldwater's aides on the committee assisted in drafting the Leahy report.

At the OAS, Honduran Ambassador Robert Martinez Cardonez called for a meeting of five regional states, including Nicaragua, to bring about a stable and long lasting settlement in the area. Martinez said that Nicaragua should participate if it is serious about seeking peace.

Nicaraguan Ambassador Edgard Parrales Castillo replied that the proposal is a U.S.-initiated "trap" to outnumber Nicaragua at a regional meeting. He said the real problem is an armed conflict "created artificially by the United States using Honduras" and he cited U.S. press reports in charging that Washington is "promoting, financing, advising and assisting" counterrevolutionary bands.

The envoy called for bilateral U.S.-Nicaraguan negotiations to deal with the conflict. In Managua, the Foreign Ministry said it is asking Mexico, Venezuela, Panama and Colombia to use their good offices to arrange a U.S.-Nicaraguan dialogue and Nicaraguan-Honduran dialogue to settle disputes.

U.S. Ambassador J. William Middendorf II backed the Honduran call for a five-way Central American meeting.

The U.S. ambassador recalled that the Sandinista leaders who took power in July, 1979, had promised the OAS to pursue "free and fair elections" and pluralism at home, and non-alignment abroad.

Middendorf charged that the Sandinistas "betrayed" those promises and made Nicaragua an "increasingly totalitarian society."

Nicaragua's Parrales, referring to reports that the Reagan adminstration is preparing to reduce Nicaragua's U.S. sugar quota and shift most of it to Honduras, charged that this is "a beautiful reward for treason."

Administration sources said that a tentative decision has been made to reduce Nicaragua's sugar quota, but that it is not likely to be announced for several weeks.

One official suggested that the administration hopes to use the threat of a sugar limitation as a carrot as well as a stick. "I'm sure the question would be reconsidered if Nicaragua wants to stop exporting revolution to El Salvador and its other neighbors," the official said.