Thousands celebrated Christmas in Bethlehem Tuesday at a time when unrest across the Middle East threatens to drive even more Christians from the cradle of their faith.

Pope Francis was to celebrate his first Christmas mass since becoming pontiff, as Christians from ancient communities in Syria flee its civil war and others struggle to rebuild after the devastating typhoon that struck the Philippines this year.

In the West Bank town of Bethlehem, the historic site of Jesus's birth, Jerusalem's Latin patriarch Fuad Twal is to lead a procession and celebrate midnight mass attended by Palestinian president Mahmud Abbas and other dignitaries.

Thousands of pilgrims and tourists made their way past Israel's controversial separation wall to reach the Palestinian hilltop town of Bethlehem, where snow remains on the ground from a rare winter blizzard this month.

A giant Santa was set up in Manger Square, outside the centuries-old Church of the Nativity, where a candle-lit grotto marks the spot where Christians believe the Virgin Mary gave birth to Jesus.

In a Christmas message last week, Twal spoke of the horrors of Syria's 33-month conflict and the suffering of Palestinians in the Holy Land, where US-brokered peace talks relaunched in July after a three-year hiatus have shown no visible sign of progress.

"As long as this problem is not resolved, the people of our region will suffer," said Twal, adding the Israel-Palestinian conflict was "a major obstacle" to Middle East stability.

The patriarch also called for a ceasefire in Syria, where an estimated 126,000 people have been killed since March 2011.

"We call on all political leaders to assume the responsibility for finding a mutually acceptable political solution that will end the senseless violence and uphold respect for the dignity of people."

Among the millions displaced by the fighting in Syria are the thousands of residents of the historic Christian hamlet Maalula, many of whom still speak the ancient Aramaic of Jesus.

"Christmas in Maalula was joyful. We would decorate the Christmas tree, and friends and relatives would get together for midnight mass. People were happy," said Juliana, a 22-year-old Maalula refugee in Damascus.

"This year, we will attend mass of course but there won't be any Christmas tree or manger. We are refugees now."

Filipinos find cheer amid storm's ruins

In the Philippines it was not war but a devastating act of nature, Super Typhoon Haiyan, which flattened entire towns and left nearly 8,000 people dead or missing.

Filipinos who survived the disaster defiantly prepared to celebrate Christmas in their ruined communities, where hogs were roasted and churches filled to overflowing.

"Nothing can stop us from welcoming Christmas even though we have lost our home," 63-year-old Ellen Miano said in Tacloban, which bore the brunt of the storm.

On a lighter note, the US government said it had officially cleared Santa Claus for entry to the United States after the authorities waived stringent livestock checks on his reindeer.

NASA astronauts meanwhile embarked on a rare Christmas Eve spacewalk to make repairs on the International Space Station.

Pope Francis was to celebrate the solemn Christmas Vigil mass in St Peter's Basilica from 2030 GMT before delivering his "Urbi et Orbi" ("To the City and the World") blessing on Wednesday at St Peter's Square -- where he first appeared after his election in March.

"Like the Virgin Mary, the Church this week is expecting a birth," the pope said in a homily on Monday.

"Is there space for the Lord or is there space only for parties, shopping and making noise?" he asked.

The 77-year-old pontiff plans to make his first visit to the Holy Land in May 2014.

Francis has voiced growing concern about the plight of Christian minorities in Syria and across the region, where the hopes of the 2011 Arab Spring uprisings have faded as radical Islamist groups have exploited the chaos following the fall of long-ruling autocrats.

"We will not resign ourselves to imagining a Middle East without Christians," the pope said in November at a meeting with Middle East patriarchs, calling for "the universal right to lead a dignified life and freely practise one's own faith to be respected".

"Syria, Iraq, Egypt and other areas of the Holy Land sometimes overflow with tears."