Gaza's deadliest-ever war cast a pall of gloom over Bethlehem on Christmas Eve Sunday, as the death toll spiraled and Israel shifted its efforts against Hamas to the besieged territory's south.

The health ministry in the Hamas-run Strip said an Israeli strike late Sunday killed at least 70 people in Al-Maghazi refugee camp, in central Gaza, and destroyed several houses.

AFP was unable to independently verify the toll, which suggests one of the deadliest strikes since the war began on 7 October. Contacted by AFP, the Israeli army said it was "checking" the report.

Health ministry spokesman Ashraf al-Qudra said the "toll is likely to rise" as many families were thought to be in the area at the time of the strike.

Christmas celebrations were effectively canceled in the occupied West Bank city of Bethlehem, revered as the birthplace of Jesus Christ, where the Latin patriarch offered a message of solidarity with the Palestinians of Gaza.

And Pope Francis kicked off mass at Saint Peter's Basilica with a call for peace.

"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," the Catholic leader said.

US President Joe Biden earlier stressed the "critical need" to protect civilians, in a call with Prime Minister Benjamin Netanyahu, who vowed Israel would "continue the war until all of its goals have been achieved", according to official statements.

As heavy fighting raged on, the Israeli army said 154 troops had died in Gaza since it launched its ground invasion on 27 October.

Ten soldiers were killed in battles on Saturday, one of the deadliest days for the Israeli side.

"The war is exacting a very heavy price… but we have no choice but to keep fighting," said Netanyahu.

As the war rages on, Christians around the world mark Christmas Eve.

Festivities are usually held in Bethlehem, where faithful believe Jesus was born, but this year the city is almost deserted, with few worshippers around and no Christmas tree erected, after church leaders decided to forego "any unnecessarily festive" celebrations in solidarity with Gazans.

The Latin patriarch of Jerusalem, Pierbattista Pizzaballa, arrived Sunday at the Church of the Nativity, clad in the traditional black and white keffiyeh.

"Our heart goes to Gaza, to all people in Gaza but a special attention to our Christian community in Gaza who is suffering," he said.

"We are here to pray and to ask not only for a ceasefire, a ceasefire is not enough… violence generates only violence."

Sister Nabila Salah from the Catholic Holy Church in Gaza — where two Christian women were killed by an Israeli sniper earlier this month according to the Latin Patriarchate of Jerusalem — struck a sombre tone.

"All Christmas celebrations have been canceled," she told AFP. "How do we celebrate when we are… hearing the sound of tanks and bombardment instead of the ringing of bells?"

At a hospital in Khan Yunis, where much of the fighting has been concentrated recently, Fadi Sayegh, whose family has previously received permits to travel to Bethlehem for celebrations, said he would not be celebrating Christmas this year.

"There is no joy. No Christmas tree, no decorations, no family dinner, no celebrations," he said, while undergoing dialysis. "I pray for this war to be over soon."

Vast areas of Gaza lie in ruins and its 2.4 million people have endured dire shortages of water, food, fuel, and medicine due to an Israeli siege, alleviated only by the limited arrival of aid trucks.

The Jordanian army said its air force had air-dropped aid to about 800 people sheltering at the Church of Saint Porphyrius in northern Gaza.

Eighty percent of Gazans have been displaced, according to the UN, many fleeing south and now shielding against the winter cold in makeshift tents.

Two Palestinian men who had been held by the Israeli army in Gaza and a medic alleged that detainees have been subjected to torture in Israeli custody, including beatings and food deprivation — charges the army has denied.

Israeli military spokesman Jonathan Conricus indicated that forces were close to gaining control in northern Gaza and that now "we focus our efforts against Hamas in southern Gaza".

The head of the UN refugee agency, Filippo Grandi, urged an end to the suffering in the third month of the war.

"A humanitarian ceasefire in Gaza is the only way forward," he wrote on X, formerly Twitter. "War defies logic and humanity, and prepares a future of more hatred and less peace."

And World Health Organization chief Tedros Adhanom Ghebreyesus similarly renewed calls for a ceasefire, saying: "The decimation of the Gaza health system is a tragedy."

On Friday, the United States allowed the passage of a UN Security Council resolution that effectively called on Israel to allow "immediate, safe, and unhindered" deliveries of life-saving aid to Gaza "at scale".

World powers had wrangled for days over the wording and, at Washington's insistence, toned down some provisions — including removing a call for a ceasefire.

The Gaza war has heightened tensions across the Middle East. Yemen's Huthi rebels have fired at cargo vessels in the Red Sea, leading the United States to build a naval task force to deter the missile and drone strikes.