SAN JOSE, Costa Rica — Arturo Cruz, the Nicaraguan rebel leader whom the United States wanted to remain as part of the contra leadership, Monday made good on his threat to quit the U.S.-backed contra alliance.
"I don't think I can contribute in any way by staying longer," Cruz told reporters outside the Costa Rican Foreign Ministry. He added that the alliance remains dominated by conservatives and their allies in the U.S. government.
He said his resignation from the directorate of the United Nicaraguan Opposition umbrella group was effective today.
In a 2 1/2-page letter delivered to newspapers in Miami and San Jose, Costa Rica, Cruz said he had failed to bring about reforms in the contra movement.
Cruz arrived here to join the other two contra leaders who form UNO's directorate for a meeting with Costa Rica's Foreign Minister Rodrigo Madrigal.
Madrigal told them of President Oscar Arias Sanchez's decision to ban UNO meetings in Costa Rica.
Arias, in a communique late Sunday, said that the UNO leaders would violate Costa Rica's neutrality if they met here to manage the finances or the military side of the contras' war to oust the Sandinistas from neighboring Nicaragua.
Cruz's resignation, coming on the heels of Arias' decision, dealt a blow to the contras' efforts to organize all of their activities against Nicaragua's ruling Sandinistas under a united civilian body acceptable to the U.S. Administration and to Congress.
The other two members of the UNO directorate, Alfonso Robelo and Pedro Joaquin Chamorro Jr., live in Costa Rica. Cruz lives in Miami, but visits Costa Rica often.
Cruz, an economist and a former official of the Washington-based Inter-American Development Bank, was once a member of the Sandinistas' ruling junta and was later Managua's ambassador to Washington. He broke with the Sandinistas, he said at the time, because of the Marxist elements of their program.
Had Feud With Calero
He has feuded with his rebel contemporary, Adolfo Calero, who is the civilian leader of the Nicaraguan Democratic Force. Cruz was at the point of resigning his UNO post last month but remained after Calero resigned instead under pressure from the State Department and was replaced by Chamorro. Calero agreed at that time with a demand of Cruz that rebel military activities be placed under the overall command of UNO's civilian leadership.
In February, Elliott Abrams, assistant secretary of state for inter-American affairs, said that it would be a "real blow" to UNO if Cruz stepped down, calling him almost irreplaceable.
The State Department had no immediate comment Monday on Cruz's resignation.
May Hurt Contra Funding
Cruz's resignation is expected to hinder the Reagan Administration's efforts to secure another $105 million in economic and military aid for the contras for next year. Congress authorized $100 million in aid this fiscal year and $27 million in non-lethal aid last year.
Robelo told reporters at the Foreign Ministry that Cruz's resignation was a loss for more moderate members of the contra movement.
"It weakens our position, but we have to continue fighting," Robelo said.
In Cruz's resignation letter, written in Spanish, he accuses the Nicaraguan Democratic Force of seeking to dominate the entire anti-Sandinista movement. He said the armed group, run by the ultraconservative Calero, had allied itself with conservatives in the Reagan Administration to lock out more moderate factions.
Lacked Political Legitimacy
Cruz said the result was that UNO had failed to earn political legitimacy and, instead, had appeared to be a tool of the United States.
"The Nicaraguan resistance remains headquartered in the United States," Cruz wrote.
"A certain faction in the government of this great nation (the United States) . . . has led to (U.S.) support for hegemonistic tendencies within UNO," Cruz wrote. "No one person alone can fight against that force."
Cruz said in his letter that he had fought to reform the contra movement in three areas: To bring the contra armies under civilian control in the alliance; to put the Nicaraguan Democratic Force's financial resources under UNO, and to reorganize the contras' assembly of exile political parties, professional and union groups.
"Just as the sad development of Sandinism . . . has brought tragedy to our people, there is a group within UNO that would perpetuate the same unwelcome trends," Cruz said.
Sources close to Cruz said one of the factors in his decision to resign now was that he had arranged a meeting last week with Enrique Bermudez, military chief of the Nicaraguan Democratic Force, to discuss bringing his troops under UNO control, but that Bermudez did not appear for the meeting.
They said Cruz then sought support for a move to fire Bermudez but found he did not have support from the Reagan Administration, Robelo or Chamorro.
Bermudez, an ultraconservative like Calero, is a former member of the National Guard of deposed Nicaraguan dictator Anastasio Somoza. Sources close to Bermudez said recently that he planned to travel to Miami to talk to Cruz this week.
Officials in the Nicaraguan Democratic Force said they were surprised at Cruz's decision to resign now as negotiations were still under way over the key issues.
Calero and other officials of the group refused to respond to Cruz's charges publicly, but privately one official said: "He has lost. He didn't get what he expected to get."