Palestinian Christians held a sombre Christmas vigil in Bethlehem on Saturday, with candle-lit hymns and prayers for peace in Gaza instead of the usual festive celebrations at the spot where they believe Jesus Christ was born.

Most years Bethlehem basks in the central place it holds in the Christian story of Jesus' life, born there in a stable because there was no room for his parents at the inn, and placed in an animal's manger, the humblest of all possible beds.

Some 2,000 years later, pilgrims usually flock to the reputed location of that stable in Bethlehem's Byzantine-era Church of the Nativity, where most Christmases there are joyful displays of lights and trees in Manger Square.

But with Israel's campaign in Gaza having killed more than 20,000 people according to health authorities in the Hamas-run enclave, the mostly Palestinian population of Bethlehem in the Occupied West Bank are in mourning too.

This year they decided to have no large tree, the usual centrepiece of Bethlehem's Christmas celebrations because of the carnage taking place only 50km away.

And in place of the usual nativity scene, as Christians call the traditional display of figurines representing the holy family, Bethlehem churches this year placed the models amid rubble and barbed wire in solidarity with the people of Gaza.

"Bethlehem is a message. It is not a city, it is a message of peace to the whole world. From this sacred place we convey a message of peace ... stop the war, stop the blood, the killing and the revenge," said Father Ibrahim Faltas, a friar at the vigil.

Meanwhile, the war has kept away the majority of expected foreign tourists hoping to celebrate Christmas in Bethlehem.

"This Christmas comes to Bethlehem in a different shape. Nowadays Bethlehem, as any other Palestinian city, is in mourning. We feel sad," said the town mayor Hanna Hanania, lighting a candle in Manger Square. (Reuters)