Pope Benedict stepped up his calls for change and a greater role for the Catholic Church in communist-run Cuba on Tuesday but was quickly rebuffed by a senior government official who ruled out political reforms in the one-party state.

As the pope's trip drew to a close and Benedict met with President Raul Castro, the Vatican also disclosed it had made a humanitarian request to Havana, raising speculation that it might be seeking the release of political prisoners or jailed American Alan Gross.

Meeting Castro at the Palace of the Revolution, Benedict also asked the Cuban leader to consider making Good Friday, the day Christians commemorate Christ's death, a national holiday, just as Castro's older brother Fidel re-instated Christmas as a holiday when Pope John Paul visited in 1998.

Former leader Fidel Castro said in a column published Tuesday night in www.cubadebate.cu he would meet with the pope briefly on Wednesday before the pontiff goes back to Rome.

Vatican spokesman Father Federico Lombardi told reporters that Fidel Castro, who ruled Cuba for 49 years before age and illness forced him to step down fours year ago in favour of his younger brother, did not attend the talks and it was still unknown if he would meet the German pope.

Cuban television showed Raul Castro and Benedict going in and out of private talks that lasted less than an hour, but they did not speak to the press.

Benedict arrived for the second papal trip to Cuba in history at a time when Raul Castro has initiated reforms to the country's Soviet-style economy with the aim of strengthening communism for the future.

He is encouraging more private enterprise and reducing the state's role, which includes the slashing of 1 million jobs from government payrolls, which is about 20 percent of Cuba's total workforce of 5.2 million.

To help deal with dislocation from the reforms, Raul Castro has embraced the Church as interlocutor on social issues and improved relations that were sour for decades after Cuba's 1959 revolution.

Some Cubans have expressed hope that economic changes would be accompanied by political change in the country where the only legal political party is the Communist Party, but Marino Murillo, a vice president in the Council of Ministers and the country's economic reforms czar, told reporters that was not in the cards.

NO POLITICAL REFORM

In Cuba there won't be political reform, he said at a news conference at Havana's Hotel Nacional, the international press centre for the pope visit. We are talking about the update of the Cuban economic model to make our socialism sustainable.

We have studied what the whole world is doing, but we will update our socialist model with very Cuban characteristics, he said in comments that were not new, but stood out in the context of Benedict's visit.

Since his arrival on Monday in the eastern city of Santiago de Cuba, the 84-year-old pontiff has spoken of Cuba's need for renewal, reconciliation and a further opening of the society, with the Church as a full partner to help the transition.

He started off with a bang on Friday when, on the flight to Mexico, his first stop, he said communism was obsolete and called for a new economic model in Cuba.

The pope is saying 'give us the possibility to use all our services, to do everything that we can do and want to do for the common good. The contribution of the church, if it becomes more vital and active, will be able to make a contribution to the well being of society,' Lombardi said.

He hopes there will be a possibility for the Church to make a commitment to do more than it can now, even in the field of communications, health care and education.

The Church lost its schools, health care facilities, much of its property and access to mass media in the years after the revolution and would like to regain some of the political and social ground it once held.

It remains the largest and most socially influential institution in Cuba outside of the government, despite years of diminution.

In its role as interlocutor, it helped broker a deal with Castro in 2010 to release 130 political prisoners and, based on its humanitarian requests on Tuesday, may want more freed. Dissidents say almost 50 remain behind bars.

It may also have sought the release of Alan Gross, jailed since December 2009 on a 15-year sentence for illegally setting up wireless Internet networks under a U.S. pro-democracy program. His imprisonment has stalled progress in U.S.-Cuba relations.

Benedict will have one more chance to appeal for change on Wednesday morning when he celebrates a public Mass in Havana's Revolution Square before returning to Rome.

The pope gave an open-air Mass in Santiago on Monday and on Tuesday, before flying to Havana, he visited the mountainside town of El Cobre to pray before an icon of the Virgin of Charity, Cuba's patron saint.

(Additional reporting by Simon Gardner and Nelson Acosta in Santiago; Editing by David Adams and Anthoy Boadle)