Vatican City - Pope Leo XIV on Thursday urged Russia and Ukraine to find the "courage" to hold direct talks and spoke of the dire suffering in Gaza in his first Christmas message to the world.

The US pope, who was elected by fellow cardinals in May after the death of his predecessor pope Francis, also condemned the "senselessness" of war and the "rubble and open wounds" it leaves behind.

Speaking to a crowd of some 26,000 people in St. Peter's Square, the pope called for "solidarity with and acceptance of those in need" in Europe, amid growing anti-immigration agitation on the continent.

"Let us pray in a particular way for the tormented people of Ukraine," he said.

"May the parties involved, with the support and commitment of the international community, find the courage to engage in sincere, direct and respectful dialogue."

Russian and Ukrainian officials have spoken separately in recent weeks to US negotiators about proposals to end the war started by Russia's invasion of Ukraine in February 2022.

Leo also addressed the dismal conditions imposed by Israel on Gaza, where hundreds of thousands of people are spending a third consecutive winter in threadbare tents while continuing to face Israeli attacks, in violation of a nominal ceasefire.

"How... can we not think of the tents in Gaza, exposed for weeks to rain, wind and cold," the pontiff said, adding that the Palestinian territory's inhabitants "have nothing left and have lost everything."

The UN has said that an estimated 1.3 million people currently need shelter assistance in Gaza and has warned of the increasing risk of hypothermia as temperatures dip, as Israel continues to block aid.