The leader of a private expeditionary force asked the Central Intelligence Agency last November to put him in touch with "gurrillas in Hondrus to fight the communist Nicaraguan government," but the agency turned his inquiry over to the Justice Department, a Senate committee was told yesterday.

The Nov. 4, 1983, letter from Thomas V. Posey, organizer of the Alabama-based Civilian-Military Assistance (CMA), was presented to the Senate Select Committee on Intelligence as part of the administration's case that it was not involved in the CMA mission to the Honduras-Nicaraguan border area that cost the lives of two American participants earlier this month.

The presentation by officials of the CIA and State and Defense departments seemed to have convinced the committee. Chairman Barry Goldwater (R-Ariz.) and Vice Chairman Daniel Patrick Moynihan (D-N.Y.) said later they were satisfied there was no U.S. government involvement in the fatal mission.

"A private citizen of this country has the right to volunteer in any cause or country any place in this world to help them, and there's nothing we can do to stop them," Goldwater said. He added, "it's been going on forever and ever," citing American volunteers in the past in Spain, Israel and China, and said even enacting laws against private missions probably would not be effective.

Anti-government guerrillas in Nicaragua who have been supported by the CIA since early 1982 have reached out to private groups for funds and training since Congress acted this summer to deny further U.S. support.

An administration official said yesterday that the insurgents have enough U.S.-supplied equipment and money, including $100,000 still not spent last month, to tide them over until Oct. 1, when CIA funding may be resumed if Congress does not expressly forbid it.

Official sources discounted claims by guerrilla spokesmen that as much as $10 million has been received within the past six months in contributions from private citizens and third-country governments. The actual U.S. estimate is closer to $1 million, one official said.

As depicted by CIA officials, Posey and his CMA were well-meaning but troublesome outsiders whose efforts to aid the "secret war" mounted against the Sandinista Nicaraguan government were anything but appreciated.

Posey, a wholesale grocer in Decatur, Ala., said he and his friends who were Vietnam veterans were motivated by "guilt about not winning" the war in Indochina. His letter to the CIA came as he was making efforts to assist the Salvadoran and Honduran governments and reflected frustration that he had been "trying like hell" to get in touch with the "gurrillas in Hondrus."

A government official said the main result of the letter was that the Federal Bureau of Investigation opened a file on Posey and his organization, and later made it plain to him through a visit by an FBI agent that he could be in danger of violating the Neutrality Act. This law, which has been sparingly enforced, makes it a crime to act on U.S. soil to aid an insurrection against a state with which the United States is not at war.

The Senate committee was told that CIA operatives with the rebels along the Honduras-Nicaragua border immediately left the encampment when members of Posey's "volunteer" group arrived there late in August and therefore they had "no advance knowledge" of their specific mission. This is reported to be standard CIA practice when unauthorized personnel arrive at a site where CIA involvement is not acknowledged.

Two of the volunteers, Dana H. Parker and James P. Powell III, were killed when a helicopter in which they were flying was shot down by Nicaraguan troops in Nicaraguan territory.

Goldwater said of the two dead Americans, "They both were veterans of the Vietnam war. I believe they were good men doing what they thought was right. Whether or not they made a good decision here, they have paid for it with their lives and we should be mindful of that."

Six lawmakers who are members of the Arms Control and Foreign Policy Caucus, meanwhile, issued a report charging a "troubling pattern of disrespect and disregard for the law" in U.S. policy in Central America.

Commenting on the Alabama-based private group headed by Posey, the report said, "The apparent failure of U.S. officials to attempt to halt the activities of CMA or other groups sending cash and aid to the contras the anti-government guerrillas adds strength to the case that the Neutrality Act may be being violated."

The report said disclosures about CMA "call into question" whether its activities violated three other laws, which were listed as sections of the Arms Export Control Act, the 1984 Defense Appropriation Act and the Foreign Assistance Act.

The Democratic-controlled House has voted repeatedly to deny further U.S. funds for the anti-government Nicaraguan guerrillas on grounds that the United States is violating international law by aiding the rebellion.

The House also has written into law a stringent ban on the use of CIA contingency funds and other special accounts to aid the Nicaraguan insurgents. It is considered likely that the administration may use contingency funds for rebel aid after this ban expires Sept. 30, unless the House manages to write it into a law that applies to the coming fiscal year.