Pope Francis in Turkey
Pope Francis sent letters to Obama and Castro to encourage talksGiampiero Sposito/Reuters

Pope Francis and the Vatican have reportedly played an important role in facilitating secret talks between the United States and Cuba to lead to a thaw in relations after decades of estrangement and embargo.

Over 18 months, a deal was negotiated between Havana and Washington during meetings in Canada, encouraged by Pope Francis who sent personal letters to Barack Obama and Raul Castro. The Vatican then held the final talks this fall.

Obama and Castro agreed in a 45-minute telephone call to put aside major differences and normalise new relations. That represented the first communication at the presidential level with Cuba since the Cuban revolution.

The deal, which was announced after the release of American contractor Alan Gross, held in Cuban prison for five years, includes the restoration of full diplomatic relations with Cuba and the opening of an embassy in Havana.

An American official said: "Pope Francis personally issued an appeal through a letter that he sent to President Obama and to President Raul Castro, calling on them to resolve the case of Alan Gross and the cases of the three Cubans who have been imprisoned here in the United States and also encouraging the United States and Cuba to pursue a closer relationship."

The letter, from the first Latin American pope, gave "greater impetus and momentum for us to move forward", the official told BuzzFeed.

The Vatican "welcomed the news" that the two countries were in talks to solve a decades-old issue.