Pope Francis contrasts Jesus with war zone children on Christmas Eve

The Pope has urged Christians to celebrate the birth of Jesus by thinking about the plight of today's children who must dodge bombs or flee in migrant boats.

Pope Francis celebrated a sombre Christmas Eve Mass in a packed St Peter's Basilica in Vatican City.

In his homily, Francis urged his flock to reflect on how children today aren't always allowed to lie peacefully in a cot.

Instead of being loved by their parents, as Jesus was, they "suffer the squalid mangers that devour dignity".

He said they were forced to hide "underground to escape bombardment ... at the bottom of a boat overladen with immigrants".

The mass, late on Saturday, was the first major event of the Christmas season.

It will be followed by Pope Francis' noon Urbi et Orbi (To the city and the world) blessing on Christmas Day.

In another appeal, Francis called for the faithful to not get caught up in the commercialisation of Christmas.

Materialism has "taken Christmas hostage," he said. "We have to set it free."

Elsewhere, Christmas Eve celebrations took place in Bethlehem, with thousands of pilgrims and tourists descending on Jesus's birthplace.

Crowds gathered in Manger Square to hear traditional Christmas songs like Jingle Bells being played in Arabic over loudspeakers.

Tourists and local Christians wandered around the square, which has been illuminated by festive red and golden lights and decorated with a large Christmas tree.

Rodrigo Reis, 23, who came from Louisville, Kentucky, said: "It's very unique, I've never seen anything like it.

"It's very meaningful. It's Christmas time, where everything started." 

The Rev Pierbattista Pizzaballa, the apostolic administrator of the Latin Patriarchate, is the temporary chief clergyman to the local Catholic population. 

He travelled from Jerusalem to Bethlehem on Saturday in a traditional procession, and said: "I am happy that the war, at least the military war, in Aleppo is finished and that for the first time in Aleppo the Christians can celebrate without fear the Christmas season. 

"I wish that they can now reconstruct, rebuild the city, not only the infrastructure but also the common relations that was a tradition over there." 

The Syrian Government assumed full control of Aleppo earlier this month when rebels agreed to withdraw from their last remaining enclave after more than four years of heavy fighting over the country's largest city.