By Philip Pullella
VATICAN CITY (Reuters) - Pope Francis will make a lightning trip to the Greek island of Lesbos on April 16, the Vatican said on Thursday, a visit aimed at supporting refugees and drawing attention to the front line of Europe's migrant crisis.
Hundreds of thousands of refugees, many fleeing war in Syria, have poured onto the Aegean island over the past year, triggering Europe's biggest humanitarian crisis in generations.
Under a contested plan, the European Union started returning newcomers to Turkey this month.
The pope has repeatedly spoken out in support of refugees and has urged Roman Catholic churches around Europe to take in migrant families. His first trip after he became pontiff in 2013 was to the Sicilian island of Lampedusa, which, like Lesbos, has received many thousands of migrants.
"It's very clear that the pope recognizes that there is a significant emergency going on," said Vatican spokesman Father Federico Lombardi.
"Just as he went to Lampedusa, which was then the front line of the Mediterranean route, now that there is this difficult, dramatic situation on the Aegean front, he naturally wants to be present to show a sense of solidarity and responsibility."
The Vatican said details of the day trip were still being worked out but that the pope would meet refugees along with Bartholomew, the Istanbul-based spiritual head of the world's Orthodox Christians, and Ieronymos II, head of the Greek Orthodox Church.
Alarmed at the recent influx or refugees, the European Union and Turkey agreed to seal off the sea route last month after Balkan states shut their borders to migrants trying to reach wealthy western Europe, stranding thousands in Greece.
Under the agreement, Turkey has said it will take back migrants and refugees who cross the Aegean. In return, the EU will take in thousands of Syrian refugees directly from Turkey and reward it with money, visa-free travel for Turks and progress in its EU membership negotiations.
Lombardi said the pope's trip to Lesbos was "a joint initiative" that will "show that various Christian churches are united when faced with great emergencies".
Theological differences and historical circumstances triggered a schism in Christianity in 1054, splitting it into a Western branch, which is mostly Catholic and Protestant, and the Eastern branch, which is mostly Orthodox.
(Additonal reporting by Michele Kambas in Athens; Editing by Crispian Balmer/Mark Heinrich)