VATICAN CITY (AP) -- Cuban President Raul Castro received a warm welcome at the Vatican Sunday from Pope Francis, who played a key role in the breakthrough between Washington and Havana aimed at restoring U.S.-Cuban diplomatic ties.

`'Bienvenido!'' Francis said in his native Spanish, welcoming Castro in a studio near the Vatican public audience hall. The Cuban president, bowing his head, gripped Francis' hand with both of his, and the two men began their private talks.

The meeting lasted nearly an hour, as the Argentine-born Francis and Castro spoke in their native Spanish.

Francis will visit Cuba in September en route to the United States.

Castro had already publicly thanked Francis for helping to bring Havana and Washington closer together after decades of U.S. government policy of strict isolation of the Communist-ruled Caribbean island. On Sunday, he stepped up his praise on Francis' push for the two nations to put enmity aside and work for reconciliation.

As he took his leave, Castro told journalists, ``I thanked the pope for what he did.''

Later, at the Italian premier's office, Castro praised Francis for his ``wisdom, modesty and all his other qualities.''

``I read all the speeches of the pope,'' Castro said.

Vatican spokesman, the Rev. Federico Lombardi, said Castro ``laid out to the pope the sentiments of the Cuban people in the wait and preparation for his upcoming visit to the island in September.''

Castro said that he will attend all the Masses that Francis will celebrate during the papal trip to Cuba.

After meeting with Premier Matteo Renzi, the Cuban leader expressed hope that his country would quickly see more fruits of the thaw between Cuba and the United States.

`'Maybe the (U.S.) Senate will take us off the list of terrorist nations'' soon, Castro told reporters.

Francis gave Castro a medal depicting St. Martin of Tours, known for caring for the destitute.

``With his mantle he covers the poor,'' Francis told Castro, saying more efforts on behalf of the poor are needed.

A  Cuban artist, Kcho, part of the Castro entourage, presented Francis with a painting of wrecked boats, and depicting a migrant in prayer. The artist told Francis he was inspired by Francis' visit to the Italian island of Lampedusa, where many migrants arrive aboard smugglers' boats.

Castro's brother, Fidel, the Cuban revolutionary leader who ruled for decades before Raul, met with Pope John Paul II at the Vatican in 1996. That Vatican encounter helped pave the way for John Paul's 1998 pilgrimage to Cuba, the first visit by a pontiff to the island.

The Vatican's general policy of opposing economic sanctions as a foreign policy tool carries appeal for Cuban leaders and people, after decades of the U.S. economic embargo. 

With the Vatican keen on protecting its Catholic followers in Cuba, Francis' predecessor, Benedict XVI also visited the island.