HAVANA (AP) _ On a day when Pope John Paul II criticized the Castro government for allowing easy access to abortion and keeping Catholic schools closed, the pope won a promise Thursday from authorities to consider freeing some Cuban prisoners.

The Vatican announced the possible concession after the pope met privately for 50 minutes with President Fidel Castro, an opportunity long-awaited by John Paul to set down his vision for his church in Cuba.

Requests from Cuban prisoners to John Paul, asking him to press for an ``act of clemency,'' were put forward by the Vatican's secretary of state in separate talks, said papal spokesman Joaquin Navarro-Valls.

The Cuban government ``received them with great attention'' because of their humanitarian character, Navarro-Valls said.

He did not say how many prisoners or whether they are among the nearly 500 political prisoners that Cuban dissidents say are being held in the country's prisons.

On his first full day on the island, John Paul went straight to the hearts and home life of the Cuban people.

When it comes to schools, ``parents ... should be able to choose,'' the pope declared, to applause from tens of thousands assembled for Mass in the dust and sweltering heat of an athletic field in the provincial city of Santa Clara, 160 miles east of Havana.

The demand for Catholic education was also believed high on John Paul's agenda for his meeting with Castro in Havana's Palace of the Revolution.

The pope and Castro met at sunset and talked privately for about 50 minutes. There was no immediate word on what they discussed.

Entering and leaving the meeting, John Paul walked slowly with the help of a cane down a red carpet, with Castro slowing his step to match the pope's pace.

``(See) how we are after seventy and something years?'' the pope said to Castro.

Castro noted the pontiff's difficulty walking, and said ``it must be because of the accident,'' referring to an injury in 1994 that required the pope to undergo hip replacement surgery.

Upon concluding their talks, they exchanged gifts and paused together at the top of broad steps outside the palace, posing for photographers outside.

Castro gave the pontiff a 120-year-old leather-bound biography of Father Felix Varela, a 19th-century priest who is considered a founder of Cuban nationalism. ``We racked our brains a lot'' to come up with something, Castro told John Paul. The book is one of nine copies in existence.

In turn, the pope gave Castro a brightly colored mosaic portrait of Christ.

In just two addresses over less than 24 hours, on the first papal visit ever to this Caribbean nation, the pontiff has been blunt in listing what he considers failings _ along with accomplishments _ of Cuba's communist system.

And in this unprecedentedly open, high-profile criticism of the 39-year-old revolution, he has found help from a surprising quarter _ the system itself.

The Communist Party newspaper, Granma, published Wednesday's papal arrival speech, including its call for ``a climate of freedom'' in Cuba. Even more important, the government is devoting hours of national television time to the papal events, giving the merely curious _ in bars, shops and homes _ a heavy helping of John Paul's message.

The Havana leadership clearly is taking a calculated risk that this may encourage dissent. But just as clearly it hopes to burnish its image with a display of tolerance and openness.

What the curious saw Thursday was an outpouring of deep emotion and affection for the pontiff after he flew in for a half-day in this heartland city.

``We feel it! We feel it! The pope is here among us!'' the crowd chanted as the ``popemobile,'' a white pickup truck topped by a bulletproof-glass compartment, wended its way toward the open-air altar.

Before, after and throughout the Mass _ even as the ailing, slow-moving pope distributed communion _ a vast chorus and orchestra filled the air with the lilting sound of Roman Catholic prayer set to maracas and drums.

At one point, they sang a song of welcome to the ``messenger of truth and hope.'' And in his homily, John Paul got quickly to his message, delivered in Spanish, about ``the social situation experienced in this beloved country.''

He denounced systems ``which, under the guise of freedom and progress, promote or even defend an anti-birth mentality.''

Abortion is free of charge and available on demand in Cuba, which has long had one of the world's highest abortion rates.

``Abortion ... is always, in addition to being an abominable crime, a senseless impoverishment of the person and of society itself,'' the pontiff said. Premarital sex, promiscuity and easy recourse to abortion have ``a profoundly negative impact on young people'' in Cuba.

In recent years, Cuban officials have accelerated a campaign to discourage abortions. They say the rate _ once one abortion for every live birth _ has been cut in half.

Castro himself, on a visit to Rome to meet the pope in 1996, told reporters, ``We do not like abortion. It is not healthy or advisable or desirable.''

But Health Minister Carlos Dotres told Granma last week that legal hospital abortions are necessary ``so we don't have deaths under poor conditions'' at the hands of unqualified abortionists.

John Paul drew the most enthusiastic reaction from the Santa Clara crowd when he called for restoration of Catholic education in Cuba.

In the early 1960s, newly triumphant revolutionaries shut down the Catholic schools, which in a largely mulatto and black nation catered to the white upper class _ most of which had left the country.

The government has certain rights in education, the pope acknowledged, but ``this does not give public authority the right to take the place of parents.''

Parents ``should be able to choose for their children the pedagogical method, the ethical and civic content and the religious inspiration which will enable them to receive an integral education,'' he said.

The Cuban church, relatively weak compared with the church in other Latin American countries, is seeking some new educational role as a way to rebuild its constituency. John Paul's mission here is, first and foremost, to strengthen the church's hand in a land where secularism, African-rooted rites and Protestantism have diminished the Catholic Church's influence.

The pope will celebrate three more outdoor Masses, in the city of Camaguey on Friday, in Santiago de Cuba on Saturday, and in Havana on Sunday.