Cuban exile Orlando Bosch, considered a guiding force of militant anti-Castro Cubans, has spoken from his prison cell in Venezuela to defend his movement's use of violence and to complain again of "miserable" treatment at the hands of the FBI and the Central Intelligence Agency.

In a rambling, written response to questions submitted to his attorney, Bosch, 49, a former Miami pediatrician, said that his movement's member groups want "to destroy the violent tyranny by all methods, and of course . . . including violence."

Bosch has been jailed in Caracas since late last year, awaiting trial on murder charges in connection with the death of 73 persons in the crash of a Cuban airliner off the coast of Barbados Oct. 6. Venezuelan authorities say they have evidence that the plane went down after a bomb planted aboard it by Cuban exiles exploded.

In addition to the Venezuelan charges. Bosch is wanted in the United States for parole violation and for questioning in connection with the assassination in Washington last September of exiled former Chilean Foreign Minister orlando Letelier.

According to sources close to the investigation, U.S. investigators believe that Cuban exiles may have killed Letelier for pay. Bosch is not believed to be a target of that investigation, but the Venezuelan government has thwarted U.S. authorities' attempts to question him.

In his letter from prison. Bosch said he visited Chile and other South American countries in late 1975 and early 1976 to forge agreements with individuals and groups "of identical purpose."

Asked whether he had received aid from the Chilean government, he said he has never and "direct or indirect relations of any kid" with Chilean authorities.

Allegedly trained by the CIA before the Bay of Pigs invasion, Bosch was a leader of anti-Castro terroists operating in Miami in the 1960s.

After being jailed six times on various charges, he was finally convicted in 1968 of firing a bazooka at a Polish ship in Biscayne Bay. He served four years of a 10-year sentence, was paroled and went underground.

When CIA activities against Castro ostensibly ceased, militant Cuban exiles became embittered. Bosch was one of the first exile leaders to turn against the CIA, bitterly denouncing the agency in the mid-1960s for "dispersing, dividing and destroying the anti-Castro revolution."

He said he is "one of the chief leaders" of the United Revolutionary Command, known as CORU. The organization reportedly was formed in Costa Rica last June during a meeting of anti-Castro groups.

"CORU is the armed branch of Cuban honor and resistance, forged in words and action," Bosch said. "CORU has its base anywhere and everywhere. For obvious reasons its headquarters is secret [but] it exists as a perfectly integrated organization."

His own fate would not affect CORU's future, Bosch said, adding that it is "very large, well organized into cells and has sufficient resources that one or 20 reverses can't destroy it."

Skeptics in the Cuban exile community in Miami have expressed doubt as to CORU's strength, theorizing that it existed only at the time of its founding.

Asked about his relations with the CIA and the FBI, Bosch said: "In the Cuban case and in mine in particular both the CIA and FBi have conducted themselves in a miserable manner. They follow us, they confiscate our arms, threatened us and they put us in jail.

"Nevertheless, New York and Miami are full of Castro infiltrators and I don't see any action against them anywhere," he added.

In his prison responses, Bosch charged that "Castro appears to be headed toward an immoral agreement with [U.S. President Jimmy] Carter," an apparent reference to Castro's statement early this year that he thinks it is possible to normalize relations between Cuba and the United States, and would be glad to talk with Carter.

Concerning his visits to other Latin American countries, Bosch said: "I visited Chile, as I've visited the Dominican Republic, Spain, Mexico and many other countries. My entries and exists to these places have always been those of a fugitive," he said.

Bosch said he went to Chile to contact Patriay Libertad, an extreme rightist organization that sources have said provided Bosch with some of his fale documents.

The Cuban exile hinted that his movement and these "democratic revolutionaries" were responsible for two terrorist attacks in Buenos Aires. Adding, ". . . is it that you have forgotten the attempt on Cuban Ambassador Emilio Aragones in Buenos Aires . . . and the blasting of the Mexican embassy in that same city when the traitor [former Mexican President Luis] Echeverria announced his visit to Havana."

Aragones escaped injury when his car was attacked in August 1975 by four men with machine guns. A bomb blast damaged the Mexican embassy in December of the same year, but there were no injuries.

Bosch's remark is apparently the first time the embassy bombing has been linked to any Cuban interest or activity.

Despite U.S. authorities' repeated requests to be allowed to question Bosch about the Letelier assassination and several bombings and deaths in Miami, the Venezuelan government hs withheld its permission.

Nor has there been any action on a renewed U.S. request, dropped in 1974 without explanation, to have Bosch returned to the United States for prosecution on the parole-violation charge.