Pope Francis meets Cuba's revolutionary leader Fidel Castro

Pope Francis, Latin America's first pope, met Cuban revolutionary leader Fidel Castro on Sunday, discussing religion and world affairs at the home of the 89-year-old retired president.

Vatican spokesman Father Federico Lombardi said the meeting lasted about 40 minutes and was "very familiar, fraternal and friendly."

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Castro's wife and several children and grandchildren were present, the spokesman said.

Francis gave Castro several of his official papal writings as well as two books on spirituality and a book and CD on the writings of Father Armando Llorente, a Jesuit priest who taught Castro in high school.

Castro gave him a copy of Fidel and Religion, a 1985 book of interviews with a Brazilian priest and writer that lifted a taboo about speaking about religion in Cuba, which was then officially atheist.

The spokesman said there were no official photographers at the meeting and the Vatican would not release pictures. He said it would be up to the Castro family to decide whether to release pictures taken with phones.

Fidel Castro, the older brother of President Raul Castro, led the Cuban government from 1959 until he resigned for health reasons, at first provisionally in 2006 and then definitively in 2008.

Thousands converge on Havana

Earlier Sunday, Pope Francis urged thousands of Cubans in Havana's evocative Revolution Plaza to care for one another and not judge each other as he opened his visit to the country amid great hopes that the key role he played in bringing aboutdetentewith the U.S. will result in changes on the island.

Believers and non-believers alike streamed into the square before dawn for Francis's mass, and they erupted in cheers when history's first Latin American pope spun through the crowd in his open-sidedpopemobile. Francis didn't disappoint, winding his way slowly through the masses and stopping to kiss children held up to him.

While most Cubans are nominally Catholic, fewer than 10 per cent practise their faith. The crowd was not as big as when St. John Paul II became the first pope to visit the island in 1998, but it drew people who seemed to genuinely want to be there and listen to Francis's message.

"This is very important for us," said Mauren Gomez, 40, who travelled about 250 kilometres to Havana from Villa Clara by bus, spending her time reciting the rosary.

In his homily delivered under the gaze of the plaza's iconic metal portrait of Che Guevara, Francis urged Cubans to care for one another out of a sense of service, not ideology. He encouraged them to refrain from judging one another by "looking to one side or the other to see what our neighbour is doing or not doing."

"Whoever wishes to be great must serve others, not be served by others," he said, explaining that, "Service is never ideological, for we do not serve ideas, we serve people."

Francis exhorted the faithful "to learn to see Jesus in every person bent low on the path of life, in all our brothers and sisters who hunger or thirst, who are naked or in prison or sick."

Many Cubans complain about the rigidity of Cuba's system in which nearly every aspect of life is controlled by the government, from cultural institutions to block-level neighbourhood watch committees. Cubans can be excluded or lose benefits if they are perceived as being disloyal or unfaithful to the principles of the revolution.

Many Cubans are also increasingly concerned about a growing inequality in the communist island, in which those with access to foreign capital live lives of relative luxury while others can barely feed themselves, generating jealousy and division within families and society at large.

"Being a Christian entails promoting the dignity of our brothers and sisters, fighting for it, living for it," Francis told the crowd. "That is why Christians are constantly called to set aside their own wishes and desires, their pursuit of power, and to look instead to those who are most vulnerable."

'A crucial moment'

Maria Regla Gonzalez, a 57-year-old teacher, said she appreciated Francis's message of reconciliation and unity for all Cubans, and said Francis was particularly able to convey it given he is Latin American and speaks their language.

"This is a crucial moment, and the pope's support for us is very important," she said. "He made a call for unity, and that's what we want."

In an important aside, Francis ended the Mass with an appeal for Colombia's government and rebels, who have been holding peace talks in Havana for over two years, to put an end to South America's longest-running armed conflict.

"Please, we do not have the right to allow ourselves yet another failure on this path of peace and reconciliation," he said.

The appeal followed the historic call he issued to U.S. President BarackObamaand Cuban PresidentRaulCastro to end their half-century of estrangement that resulted in the restoration of diplomatic relations this summer.

Since then, the two leaders have reopened embassies in each other's countries, held a personal meeting, had at least two phone calls and launched a process aimed at normalizing ties in fields ranging from trade to tourism to telecommunications.

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The Vatican has long opposed the U.S. trade embargo on the grounds that it hurts ordinary Cubans most, and is clearly hopeful that detente will eventually lead to a lifting of sanctions.

But only the U.S. Congress can remove the embargo. Francis will visit Congress next week at the start of the U.S. leg of his trip, but it's not known if he will raise the issue there.