People donned Santa caps on beaches, ski slopes and streets around the globe on Monday to celebrate Christmas, with Israel's war on Hamas and Russia's invasion of Ukraine casting a shadow over one of the world's favorite holidays.

Red and white Santa outfits appeared on surfers from Australia to Florida, on bicyclists in the smog-filled streets of New Delhi and intrepid souls braving chilly Channel waters for a holiday dip near Britain's Dover.

Pope Francis kicked off the global celebrations with a sombre call for peace during Christmas Eve mass at the Saint Peter's Basilica at the Vatican.

"Tonight, our hearts are in Bethlehem, where the Prince of Peace is once more rejected by the futile logic of war, by the clash of arms that even today prevents him from finding room in the world," said the pope. who was due to lead a Christmas Day mass later on Monday.

The biblical city in the occupied West Bank, where Christians believe Jesus Christ was born in a stable more than 2,000 years ago, effectively cancelled the annual Christmas celebrations that normally draw thousands of tourists.

The town did away with its giant Christmas tree, marching bands and flamboyant nativity scene this year, settling for just a few festive lights.

In the centre of town, a huge Palestinian flag had been unfolded with a banner declaring that "The bells of Bethlehem ring for a ceasefire in Gaza".

"A lot of people are dying for this land," said Nicole Najjar, an 18-year-old student.

"It's really hard to celebrate while our people are dying."

The Latin patriarch of Jerusalem, Pierbattista Pizzaballa, said: "We are here to pray and to ask not only for a ceasefire, a ceasefire is not enough, we have to stop these hostilities and to turn the page because violence generates only violence".

In Syria, churches limited celebrations to prayers in solidarity with the Palestinians.

The Hamas attack on 7 October left around 1,140 people dead in Israel, most of them civilians, according to an AFP tally based on the latest official Israeli figures.

The Palestinian militants also abducted around 250 people, 129 of whom Israel says remain in Gaza.

Israel retaliated with a sustained bombardment and ground invasion of Gaza, where 20,424 people have been killed, mostly women and children, according to the latest toll from the territory's Hamas-run health ministry.

New Christmas Day

Ukraine, invaded by Russia nearly two years ago, is celebrating Christmas on December 25 for the first time, jettisoning the traditional Orthodox date of 7 January, which is feted in Russia, as a snub to Moscow.

"We believe that we really should celebrate Christmas with the whole world, far away, far away from Moscow. For me that's the new message now," said one smiling parishioner in Odesa, Olena, whose son is a medic on the front line.

The date change — moving away from the Julian calendar favoured by the Orthodox Church — is part of moves since the invasion to remove traces of the Russian and Soviet empires.

The Ukrainian military said that it had shot down 28 of the 31 drones that Russia launched on Christmas day at its neighbour, with no casualties reported.

Surfing Santas

In countries not afflicted by war, festive revellers opened presents and donned the red and white Santa hats for a shot of holiday cheer.

In Sydney, Australia,  residents and tourists headed to the beach, wearing the woolly red hats despite the heat in the Southern Hemisphere's summer.

In Florida, thousands descended on Cocoa Beach for the annual "Surfing Santas" celebration that raises funds for a charity helping cancer patients travel for treatment and the local surf museum.

In Sri Lanka, President Ranil Wickremesinghe granted an amnesty to more than 1,000 convicts and released them from jails across the country to mark Christmas, prison officials said.

Prayers in Turkey

In southern Turkey, much of which was devastated by an earthquake in February, faithful prayed for new beginnings.

"It's important for us to celebrate the birth of Jesus. but it's a very sad Christmas," said Vehbi Tadrasgil, a 55-year-old who lost his wife and two of his three children in the quake that killed at least 50,000 people in Turkey and more than 5,000 in neighbouring Syria.

"I hope that their souls are here, I am certain that our prayers rise to them," he said in front of the ruins of a church at Antakya.

Twenty kilometres (12 miles) down the coast in Samandag, a generator powered the lights on a tree in front of the Saint-Ilyas church, which survived.

"After the earthquake, our community — 400 families — was annihilated. With this Christmas, we want to wish everyone rebirth, love, joy and peace. We must move forward, rebuild a new life," said Father Yumurta.

"They say that with the birth of the child Jesus, a new life begins, a new beginning. For us too, here, it will be a new beginning," he said.