BEJUCAL, Cuba (AP) - Waving Vatican flags and singing songs to their patron saint, hundreds of Cuban Catholics crowded into a tiny church Sunday for one of a series of Masses that are stirring enthusiasm for a papal visit.

It was to have been an open-air Mass, but - in a sign of lingering tensions between the Roman Catholic Church and the communist government - local authorities ordered the service to be held behind church walls, parishioners and church sources say.

Some 500 people poured into the sanctuary to gaze upon the image of the Virgin of Charity - Cuba's patron saint - and hear Cardinal Jaime Ortega call on them to prepare for Pope John Paul II's visit in January.

Ortega has celebrated several open-air Masses attended by hundreds - beginning with one outside Havana's cathedral last month - extraordinary events in a country where public worship has been banned since the early years of the 1959 revolution.

"We have celebrated the previous Masses under the Cuban sky, which is your sky, which is ours,'' Ortega said. "Today we have to celebrate inside. But here we are.

"Despite the limitations that keep us from demonstrating our love publicly ... we show you all of our affection,'' the prelate said to loud applause. "And we prepare for the visit of John Paul II to Cuba.''

Although he didn't say why the Mass was not held outside, parishioners and church sources said Ortega's office had received word from local officials in this town near Havana that the service had to be indoors.

"Apparently the local authorities were not comfortable with it because these outdoor celebrations are not usual,'' said Laura Peralta, 54, who was wed in the church, celebrated baptisms there and had her two sons married by a priest.

"Still, we have never been harassed because of our faith, all these years,'' she said. "And now we are waiting for the pope with open hearts.''

It was not clear if other Masses would have to be held indoors. The government granted permission for 14 open-air Masses this fall as part of the church's campaign before the pontiff's Jan. 21-25 visit.

Cuba was officially atheist from the early 1960s until 1992, and religious believers were banned from the party, the military and several professions. Scores of priests were expelled, Catholic families sent their children abroad, and the communist government expropriated Catholic schools and even cemeteries.

Since the collapse of Cuba's Soviet bloc allies, however, officials have softened their approach toward religion.

In 1991, Catholics and other believers were granted permission to join the Communist Party. President Fidel Castro called his celebrated meeting with John Paul a year ago "a miracle.''

But the government apparently remains uncomfortable with public worship.

Public religious processions - so popular throughout Latin America and the Caribbean - have been banned since a clash between Catholics and government forces left a young man dead in 1961.

"We have not had public celebrations in Cuba in so many years,'' said the Rev. Gabriel Torres Salazar, parish priest at St. Lazarus Church in nearby El Rincon. "We await the pope's arrival with much emotion.''

Castro's government is devoting large amounts of energy to the papal visit in hopes that it will be a financial and public relations success for an economically ailing and politically isolated country.

"Fidel Castro has a lot to gain from the papal visit. He is hoping that it will give his country increased legitimacy,'' said Wayne Smith, a former diplomat and Cuba specialist. "The pope hopes that the parameters for the church will be expanded.''

The church has never been strong in Cuba, where about 85 percent of the population was nominally Roman Catholic before Castro took power in 1959. Church authorities now say that perhaps half of the population identifies with Roman Catholicism and may even participate in some rites, including baptism.

However, the percentage of practicing Catholics is much lower and Cuba today is a largely secular society where only a scattering of worshippers show up in most churches for Sunday Mass.

AP-NY-10-12-97 1754EDT