Pope Francis has warned that Europe's refugee crisis is just the "tip of the iceberg".
He added that the mass influx of migrants from Syria and the surrounding areas was fuelled by an "unjust" global economic system forcing hundreds of thousands of people to flee war and poverty in search of better lives.
In an interview with a Portuguese Catholic radio station, Pope Francis recalled that the Bible requires that strangers be welcomed, though he acknowledged security precautions must be taken into account in today's world.
"It's true that 400 kilometres from Sicily, there is an exceedingly cruel terrorist guerrilla group, and it's true there's the danger of infiltration," he told Radio Renascenca in an apparent reference to Islamic State extremists.
Francis repeated his call for parishes around the world to welcome in a migrant family, and said two refugee families have been identified to move into Vatican housing. They can stay "as long as the Lord wants," he said.
He applauded those European countries that had welcomed in migrants and warned what awaits those that don't: "On Judgment Day, we already know what we'll be judged on," he said, reciting the Biblical verse from Matthew 25: "When I was hungry, did you give me food?"
Those countries that answered "Yes" - "I congratulate them. They'll pass the test," he said.