Pope Francis wants to take back to the Vatican a number of refugees after his landmark visit Saturday to the island of Lesbos, an official of Greece's state refugee coordination agency said.

The refugees are expected to be among "vulnerable groups" who arrived on Lesbos before an EU-Turkey deportation deal took effect in March, the official told AFP, without specifying whether this would take place immediately after the pope's visit or at a later stage.

Greek state television ERT said three families currently staying at the open camp of Kara Tepe on Lesbos and who were chosen in a draw would be the ones to go.

The pontiff, who has shown a strong interest in the plight of thousands of refugees who have risked their lives to reach Europe, is on a five-hour visit to Lesbos, the frontline island in Europe's migration crisis.