The meeting between the Pope and Castro will take place "in a strictly private manner" in the study of the Paul VI audience hall, Jesuit Father Federico Lombardi, Vatican spokesman, said May 5.

In a statement, Father Lombardi also recalled that Castro "publicly thanked the Pope for his role in fostering the rapprochement" between Cuba and the United States.

In December, Castro and U.S. President Barack Obama announced that their nations were working toward re-establishing official diplomatic relations. Both leaders credited Pope Francis with helping to secure the deal through his letter-writing and by hosting a secret meeting at the Vatican between Cuban and U.S. representatives last fall.

The Pope is expected to travel to Cuba before his three-city tour of the United States Sept. 22-27. Though the precise dates and itinerary of his Cuban visit have yet to be issued, it would be the second visit of a pope to Cuba in three years; Pope Benedict XVI visited in 2012.

Visiting Cuba and the U.S. on the same trip signals that Pope Francis' continued interest in the normalization of relations between the two countries.

The United States first imposed a trade embargo on Cuba in 1960 in response to the human rights abuses that followed the Marxist revolution that put Fidel Castro in power the previous year. The embargo was expanded in subsequent years.