Pope Francis has expressed his concerns for the welfare of migrants trying to reach Europe, saying the seas of the Mediterranean and the deserts of North Africa have become ‘cemeteries’ for them.

The Pope was speaking to journalists on his flight home from Portugal where he had held a mass for 1.5 million people to mark World Youth Day.

He told reporters the migration issue would be discussed thoroughly when the Diocese of Marseille holds its Mediterranean Meetings event from 18 to 24 September. Pope Francis will participate in some of the meetings in September where senior clerics and politicians will discuss economic equality, migration and climate change.

The remarks come two weeks after the leader of the world’s 1.3 billion Roman Catholics called on global leaders to help migrants stranded in the deserts of North Africa, and also recalled extreme climate events and the need to address global warming.