From an 11-story building in central Havana, Cuban intelligence agents have long monitored the Roman Catholic Church, enrolling spies in seminaries, recruiting parish employees and photographing Masses, three defectors say.

And if Armed Forces Minister Raul Castro's repeated boast is true, one spy either posed as a priest or may have gone through a seminary and become a ``real'' priest, one defector said.

The revelations come in the wake of claims by Cuban Catholics that they have been subjected to increased monitoring -- although not harassment -- by government agents as they prepare to receive Pope John Paul II today for his historic five-day visit to the island.

None of the defectors wished to be identified by name. One is a former army colonel who served as an aide to Raul Castro, and the others are former top officers of the Interior Ministry, in charge of national security.

The three, interviewed separately, gave similar descriptions of the offices, tactics and philosophy that Cuba uses to spy on all religious groups, but especially on the 4 1/2-million-member Catholic Church.

``The church was always seen as a danger, because it is the only force inside the country capable of bringing people together and even organizing a subtle form of resistance,'' one Interior Ministry defector said.

The Ministry, known in Cuba as the MININT (an acronym for Ministerio del Interior), has 100,000 employees and three million collaborators in a nation of 11 million people, according to a 1994 book by Juan Antonio Rodriguez Menier, a major who defected 11 years ago.

Its spying tasks are split between an Intelligence Division that monitors and recruits agents abroad and a Counterintelligence Division that monitors potential counterrevolutionaries inside Cuba.

The Intelligence Division office that spies on religious groups or leaders abroad usually has six or seven staffers and is commanded by a young lieutenant colonel. The office has long been based in a building on the corner of Linea and A streets in Havana's Vedado sector, the defectors said.

The Counterintelligence office that spies on the church inside Cuba usually had 10 to 15 staffers and has been under the command of a senior lieutenant colonel. The office has been based for decades in an 11-story building on 21st Street, near Havana's Nacional Hotel.

The office is part of a larger department that monitors the ``ideological sector,'' which includes Cuban writers, painters, musicians and religious people from Afro-Cuban Santeros to Roman Catholics.

Department Four

Defectors said this office, like all others in counterintelligence, continually changes its name to confuse U.S. spies but is almost always referred to by the name it first used back in the 1960s -- Department Four.

Department Four sent several agents to enroll in Catholic seminaries in the 1980s and apparently recruited many churchgoers, said the defector who once served as Raul Castro's aide and had access to his correspondence.

He added that Raul often boasted that Department Four had once placed an agent as a priest, although it was not clear whether the agent merely posed as a priest or went through the full process of becoming a priest.

``Raul many times said things like, `We got him trained up to be a priest' or talked of operations where `We supplied the priest,' '' the former aide said.

In a sign of Cuba's preoccupation with the Catholic Church, two of the defectors said Department Four began tightly monitoring the annual religious procession to Havana's El Rincon shrine as turnout mushroomed in the early 1990s.

``The numbers went from 20,000 to something like 80,000. And MININT was counting them almost one by one, listing the known personalities who attended and filming them, ostentatiously, to intimidate,'' one defector said.

Numbers dropping

Turnout at El Rincon peaked in 1994, when the Cuban economy hit rock bottom following the end of Soviet subsidies. The numbers have dropped each year since then, with the economy's snail-paced recovery.

The former Raul Castro aide recalled another Department Four operation launched to counter a strong Catholic revival, especially among youth, in Cuba's south-central city of Trinidad in 1984-85.

``At a time when people in the Communist Party were seeing religion as something for old people, the church in Trinidad was attracting a strong number of young people with movies, dances and candy,'' he said.

Department Four was ordered to step up its covert spying in Trinidad, the defector said, and to coordinate a string of municipal government programs that competed for the youths' support and eventually undermined their church attendance.

All three defectors mentioned the case of Father Miguel Loredo, a Cuban priest who served 10 years in prison for sheltering an anti-Castro activist who shot and killed two people during an attempted plane hijacking in 1966.

`He was innocent'

``I helped frame Loredo. He was innocent,'' Daniel Alarcon, a Cuban army colonel who defected in France two years ago, said in a recent telephone interview. Alarcon and Loredo had an emotional reunion in Rome last fall.

But the defector said such cases of strong-arm tactics were the exception, adding that Cuban intelligence agents have seldom used raw methods such as blackmail and prefer more subtle approaches.

Cuba almost never recruits agents abroad with monetary offers, the defectors said, mostly because it's too poor to afford such payments, but also because it believes that ``a paid agent is not a dependable agent.''

Cubans inside the island are sometimes offered material rewards, one defector said -- not cash, but job promotions, access to special stores and protection from arrest if they're caught dealing in the black market.

Most recruitments, both at home and abroad, are carried out based on ideology, the defectors said, with the Cuban agents playing on their targets' nationalism or identification with the stated goals of the revolution.

``In the case of a priest or a parish worker, we would point out the coincidences in the church and revolution's criticisms of capitalism,'' one defector said. ``We would tell them, `Even if you're not a communist, you can see that Cuba has a system that is against injustice, and we need your help to make sure we know what the church is thinking and there are no misunderstandings.' ''