Pope Francis played a key role in brokering a deal to open relations between the United States and Cuba after more than half a century of hostility says the president of the United States.

President Barack Obama thanked the Pope on Wednesday for his role in opening up of Washington's relations with Havana and the release of U.S. citizen Alan Gross from Cuban custody.

"His Holiness Pope Francis issued a personal appeal to me and to Cuba's president, Raúl Castro, urging us to resolve Alan's case and to address Cuba's interests in the release of three Cuban agents, who've been jailed in the United States for over 15 years," Obama said.

A senior U.S. administration official said that the appeal from the Pope was "very rare" and unprecedented, Time Magazine reported.

"The move is perhaps Pope Francis' boldest foreign policy move yet," Time commented.

For his part Pope Francis congratulated the governments of the United States and Cuba, as they announced the two countries will start talks on resuming diplomatic relations.

A statement from the Vatican Secretariat of State said that in recent months the Pope had written to both Cuban President Raul Castro and U.S. President Barack Obama, inviting them to "resolve humanitarian questions of common interest."

"The Holy See will continue to assure its support for initiatives which both nations will undertake to strengthen their bilateral relations and promote the well-being of their respective citizens," the statement said.

Although some Catholic activists have been persecuted in Cuba the Vatican has over a number of papacies sought to foster relations with the communist State.

Pew Research Center says that more than half the Cuban population is Catholic.

In 1998, Pope John Paul II became the first pope to visit Cuba. Then, Pope Benedict XVI visited Cuba in 2012. During that visit he urged Cuba to "build a renewed and open society, a better society, one more worthy of humanity and which better reflects the goodness of God."