HAVANA, Cuba (AFP) — Pope Francis delivered mass Sunday before hundreds of thousands of fans and faithful on Havana’s iconic Revolution Square, calling Cubans to serve the most downtrodden and warning them that “service is never ideological”.

The pope’s homily did not directly address Cuba’s political situation or the nascent rapprochement he helped broker between the communist island and the United States, the next international stop on his most high-profile trip to date.

But he warned against both ideology and an every-man-for-himself mentality, at a time when Cuba faces a delicate period of economic and political transition.

“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,” he told the crowd, speaking beneath a towering sculpture of his fellow Argentine Che Guevara’s iconic silhouette.

“We need to be careful not to be tempted by another kind of service, a ‘service’ which is ‘self-serving’.” he said.

“Service is never ideological, for we do not serve ideas, we serve people.”

He paid tribute to Cubans as “a people with a taste for parties, for friendship, for beauty”.

“It is a people which has its wounds, like every other people, yet knows how to stand up with open arms, to keep walking in hope,” he said.

Hundreds of excited Cubans and foreign visitors camped out overnight on the sprawling square to see the first Latin American pope.

As he arrived, the Argentine pontiff leaned out from his white open-air vehicle to grasp the hands of festive onlookers and wave to the crowds gathered under the cloudy sky.

Cuban President Raul Castro and Argentine President Cristina Kirchner were among those in attendance.

The pope, who arrived on the communist island Saturday, is following in the footsteps of his predecessors John Paul II and Benedict XVI – a remarkable amount of papal attention in 17 years for a country where only 10 per cent of the population describe themselves as Catholic.

“It’s very exciting to see Pope Francis. He’ll be the third pope I’ve managed to see, but I’ve never been so close. We’re all hoping to receive his mercy,” said Maria Eugenia Paulina Prieto, 56, who sings in a choir that will perform during the ceremony.

The pope’s eight-day tour, which will take him on his first-ever visit to the United States, follows the announcement of the US-Cuban rapprochement, which paved the way for the estranged neighbours to renew diplomatic relations in July.

Francis, who arrived in Havana Saturday and heads to Washington Tuesday, helped facilitate that moment in secret negotiations.

Just ahead of the pope’s trip, the United States announced a further loosening of restrictions on business and travel with Cuba – a move that Havana’s archbishop, Cardinal Jaime Ortega, said he believed was inspired by Francis’s visit.

“It’s an extraordinary sign, and I think it’s related to this visit,” he told Vatican Radio.

After mass, the pope will meet with Castro, then preside over vespers at Havana Cathedral before holding an unscripted exchange with young Cubans — a demographic feeling the pain of the communist island’s difficult economic transition.

Francis may also meet Castro’s older brother and predecessor Fidel, the 89-year-old father of Cuba’s 1959 revolution.