Pope Francis is due to visit the Greek island of Lesbos to show support for refugees trying to reach Europe.
He will visit a camp where more than 3,000 people awaiting either asylum or deportation to Turkey are being held
Lesbos has been the main entry point for many among about a million people who entered Europe over the past year.
Thousands are now stuck on the island after last month’s controversial deal between Europe and Turkey to try to stem the flow.
The Vatican insists the pontiff’s five-hour visit is purely humanitarian and religious in nature and should not be seen as a criticism of the deportations.
On the eve of his visit to the Moria detention centre, one Syrian attempted to kill himself after being told he would be deported back to Turkey but was prevented by police, reports the BBC.
Migrants later demonstrated, demanding better treatment and to stay in Europe.
The Greek authorities have not yet commented on the suicide attempt, which was confirmed by non-governmental organisations on the island.
The man was among four Syrians who have now appealed against their deportation orders.
However, some Syrians on Lesbos say they are terrified by the thought of returning to Turkey because of reports that hundreds of Syrians have been forcibly returned from Turkey to Syria.
Turkey has denied sending back any refugees against their will.
Refugees and migrants also complain of overcrowded conditions and a lack of food.
