Pope Francis urges compassion for children at Christmas

Vatican City: Pope Francis urged the world's 1.2 billion Catholics to feel compassion for children, notably victims of war, migration and homelessness in his Christmas Eve mass but also those "not allowed to be born".

Addressing a 10,000-strong crowd late Saturday, the pontiff urged worshippers to celebrate "authentically", by acknowledging "the fragile simplicity of a small newborn" and "the tender affection of the swaddling clothes".

"Let us allow the child in the manger to challenge us, but let us also allow ourselves to be challenged by the children of today's world," he said, speaking in St. Peter's Square.

Many children have died this year while attempting the perilous Mediterranean migrant crossing to Europe which has claimed more than 5,000 lives in 2016 alone.

Thousands of traumatised Syrians including children meanwhile left the former rebel enclave of Aleppo this week after four months of suffocating siege.

Children are "hiding underground to escape bombardment" or "on the pavements of a large city, at the bottom of a boat overladen with immigrants", the pontiff said, before reiterating his opposition to abortion.

"Let us allow ourselves to be challenged by the children who are not allowed to be born, by those who cry because no one satiates their hunger, by those who do have not toys in their hands, but rather weapons," he said.

And in an echo of his well-established criticisms of materialism, Francis also urged the faithful to avoid indifference, "when Christmas becomes a feast where the protagonists are ourselves, rather than Jesus".

The pope, who celebrated his 80th birthday a week ago, has made simplicity and modest living the hallmarks of his papacy.

On Sunday, Francis will deliver his fourth Christmas message to the faithful massed in St. Peter's Square.