Shortly after the unsuccessful Bay of Pigs invasion of Cuba in April, 1961, the FBI began a campaign to infiltrate pro-Castro groups in the United States and publicly discredit their, leaders, by such means as setting them up with prostitutes, newly released FBI documents have revealed.

The anti-Castro campaign was part of the FBI's massive counterintelligence program (Cointelpro) to neutralize and disrupt domestic groups and individuals known to be critical or American policies.

Cintelpro documents realeased yesterday under a Freedom of Informatin Act request show that in June, 1961, FBI Director J. Edgar Hoover approved "establishing counterintelligence programs in Cuban field in an attempt to disillusion current members of such pro-Castro groups as July 26 Movement and Fair Play for Cuba Committee."

The documents do not mention Lee Harvey Oswald, the 1963 assassin of President Kennedy, although he claimed membership inthe Fair Play for Cuba Committee and said he had opened a New Orleans branch. Shortly after the Nov. 22, 1963, assassination, the group disclaimed Oswald as a member. The Warren Commission later concluded that he had sought and been granted membership in May, 1963.

The documents reveal a systematic pattern of disruption similar to Cointelpro operations against such groups as the Socialist Workers Party and the Black Panther Party.

The New York office of the FBI, which originated the program, sought to "create and foster distrust and antagonism among the officers," and also recommended using city and state laws, such as fire, health, travel and tax regulations.

An Aug. 8, 1961, memo from the New York office (NYO) to the FBI director described "confidential sources" setting up "dates" with leaders of the Fair Play for Cuba Committee.

"The NYO will make the necessary arangements with local police," the memo said, "to possibly have (deleted) picked up on local charges in the event he places himself in a compromising position through his association with professional prostitutes."

If that didn't work, the memo said, the bureau would consider giving the prostitutes' names to the local vice squad, along with the instruction to "discreetly indicate that (deleted) was the source of the information regarding the arrest . . .

"In either event," the memo concluded, "the NYO is of the opinion that valuable ramifications might result to the benefit of this bureau among the officials of the Fair Play for Cuba Committee through the embarrassment brought upon (deleted)."

To "compromise" the leadership of the July 26 Movement, the bureau wrote a phony letter to he Movimiento Revolucionario in Havana, accusing a key leader in the New York group of embezzling movement funds. The letter suggested a "total reorganization" of the executive board, because all the members had learned of the "theft" and had lost their faith in the current board.

"(Deleted) is nothing more than a counterrevolutionary worm," a draft of the phony letter said, "and his attitude has destroyed the foundations of the Movement, but there is still time to try him and let him serve as a severe example to those who make trouble for the Revolution."

The Philadelphia office of the bureau got word through informants that the July 26 Movement leaders distrusted each other, a turn of events too good to pass up. It responded with another phony letter, written in Spanish and mailed from a Latin section of New zYork.

The letter, signed "Two loyal Fidelistas," accused several leaders of being paid FBI informants, and said one had been "on the imperialist payroll" for several months. The letter said one leader, whose name was deleted from the FBI draft, "is paid in 5 and 10 dollar bills and meets the FBI at a subway station."

An October 31, 1961, memo from the director to various field offices noted that movement leaders fled to Canada rather than surrender FBI-subpoenaed documents. To fill the leadership vacuum, the memo said, "every opportunity must be taken to place aggressive, knowledgeable informants in important positions within the movement. Confidential informants should . . . interjected themselves as candidates for positions within the local and national administration of the movement."

The Cuban phase of Cointelpro lasted at least until October, 1970, the last dated entry in the Cuban file. This entry was a phony letter to a Tampa newspaper alleging that a "pro-Castr" leader, active in Florida, was a dupe of the Communists.