Christmas revellers around the world donned red and white Santa hats, offered meals to the homeless and lit candles on Wednesday, as Pope Francis launched observation of the global holiday with a sombre mass in the Vatican.

At Saint Peter's Basilica, Francis used his Christmas Eve mass to urge Christians to think "of the wars, of the machine-gunned children, of the bombs on schools or hospitals" as this year's Christmas once again takes place under the shadow of Israel's war on Hamas and Russia's invasion of Ukraine.

His remarks come just days after he denounced the "cruelty" of Israeli strikes, which prompted objections from Israeli diplomats.

Francis is due to deliver his traditional Christmas Day blessing, Urbi et Orbi (to the city and the world), at midday on Wednesday, while in the biblical birthplace of Jesus, the Israeli-occupied West Bank city of Bethlehem, observations of the holiday have been muted.

For the second year in a row, Bethlehem has done away with its giant Christmas tree and the elaborate decorations that normally draw throngs of tourists, settling for just a few festive lights.

"This year we limited our joy," Bethlehem mayor Anton Salman told AFP.

Prayers, including at the Church of the Nativity's famed midnight mass, will still be held in the presence of the Catholic Church's Latin patriarch, but the festivities will be of a more strictly religious nature.

The patriarch, Archbishop Pierbattista Pizzaballa, told a small crowd on Tuesday that he had just returned from Gaza, where he "saw everything destroyed, poverty, disaster".

"But I also saw life -- they don't give up. So you should not give up either. Never."

At Manger Square, in the heart of the Palestinian city, a group of scouts held a parade that broke the silence.

"Our children want to play and laugh," read a sign carried by one of them, as his friends whistled and cheered.

Other banners said: "We want life, not death", and "Stop the Gaza genocide now!"

Jerusalem resident Hisham Makhoul said spending Christmas in the holy city offered an "escape" from the Israel-Hamas war, which has raged for more than 14 months in the Gaza Strip.

"What we're going through is very difficult and we can't completely forget about it," said Makhoul of the plight of Palestinians in the besieged territory.

Gaza and Syria

About 1,100 Christians live in Gaza, which is separated from the West Bank by Israeli territory.

Hundreds of Gazan Christians gathered at a church to pray for an end to the war.

"This Christmas carries the stench of death and destruction," said George al-Sayegh, who for weeks has sought refuge in the 12th-century Greek Orthodox Church of Saint Porphyrius in Gaza City.

"There is no joy, no festive spirit. We don't even know who will survive until the next holiday."

In a message to Christians all over the world, Israeli Prime Minister Benjamin Netanyahu thanked them for supporting Israel's fight against the "forces of evil".

Elsewhere in the Middle East, hundreds of people took to the streets in Christian areas of Damascus to protest the burning of a Christmas tree in a Syrian town, just over two weeks after Islamist-led rebels ousted president Bashar al-Assad.

"If we're not allowed to live our Christian faith in our country, as we used to, then we don't belong here anymore," said a demonstrator who gave his name as Georges.

Santa tracker

In Germany, Christmas was also a grim affair for many families after a deadly attack at a market, prompting President Frank-Walter Steinmeier to issue a message of healing.

"Hatred and violence must not have the final word," he said.

In Buenos Aires, a Christmas solidarity dinner for the homeless fed around three thousand people at a time when more than half of Argentina's population is affected by poverty.

"To say that it is a special year because there is more and more poverty is sad, but it is true," Mariana Gonzalez, spokesperson for the Movement of Excluded Workers, one of the organisers, said.

Still, the atmosphere was joyful with floating balloons, music and clowns, as elsewhere on Christmas Eve families shared meals and gifts.

In the United States, where the annual tradition of "tracking" Santa Claus swung into action, a US Air Force general said there was no need to worry that recent mystery drone sightings might affect deliveries.

General Gregory Guillot's reassurances came as the joint US-Canadian North American Aerospace Defense Command reported that Santa and his reindeer were making stops across Asia, including Japan and North Korea.

"Of course, we are concerned about drones and anything else in the air," NORAD commander Guillot told Fox News. "But I don't foresee any difficulty at all with drones for Santa this year."

And in Paris, worshippers gathered at the Notre Dame cathedral for the first Christmas mass since its reopening following a devastating fire in 2019.

"We got here early to attend 4:00 pm mass, and to get a good spot. It's a superb monument," said Julien Violle, a 40-year-old engineer who travelled to Paris from Switzerland along with his two children.