Mutual fears between immigrants and their new communities are understandable, but must not prevent new arrivals from being welcomed and integrated, Pope Francis said on Sunday in a special Mass to mark the World Day of Migrants and Refugees.

Francis, a keen defender of the rights of migrants, was addressing a congregation including migrants and refugees from some 50 countries, whose flags festooned the area around the altar in St. Peter’s Basilica at the Vatican.

As politicians and civil society grapple with the mass movement of people around the world, with flashpoints including in the Mediterranean, and between Myanmar and Bangladesh, the Pope has repeatedly urged support for those who migrate.

Argentina-born Francis, who was the first non-European elected to the post in nearly 1,300 years, has criticised President Donald Trump’s stated intention to build a wall to stop illegal migrants crossing the U.S. border with Mexico.

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