Pope Francis has said the world is suffering from a "famine of peace", in his annual Christmas Day message from the Vatican.
He called for a end to the "senseless war" in Ukraine, condemning what he said was the use of "food as a weapon" of war.
Ukraine shipped about 30% of the world's wheat and prices have jumped since the Russian invasion in February.
It was Pope Francis' 10th Christmas Day address since he assumed the papacy.
While the war in Ukraine occupied much of his 10-minute speech, he spoke of "a grave famine of peace also in other regions and other theatres of this Third World War".
He singled out conflicts and humanitarian crises in the Middle East, Myanmar, Haiti, and the Sahel region of Africa.
The pontiff also prayed for "reconciliation" in Iran, where mass anti-government protests have swept the country for more than three months. The protests there have been met by a crackdown, with more than 500 people, including 69 children, killed, human rights groups say.
Speaking from a balcony at the basilica overlooking St Peter's Square, the 86-year-old Pope lamented the human cost of war. He urged not to forget those "who go hungry while huge amounts of food daily go to waste and resources are being spent on weapons".
"The war in Ukraine has further aggravated this situation, putting entire peoples at risk of famine, especially in Afghanistan and in the countries of the Horn of Africa," he said.
"We know that every war causes hunger and exploits food as a weapon, hindering its distribution to people already suffering."
The Pope said "those who hold political responsibilities" should lead the way to make food "solely an instrument of peace".
His message was followed by the customary Urbi et Orbi (To the City and to the World) blessing, recited in Latin and traditionally in many other languages as well.
An earlier report adds: Pope Francis has condemned human "hunger for wealth and power" at Christmas Eve Mass in the Vatican, seemingly referring to the war in Ukraine and other conflicts.
"How many wars have we seen!" he said, adding that the main victims were "the weak and the vulnerable".
"I think above all of the children devoured by war, poverty and injustice," the pontiff added.
He was addressing worshippers at St Peter's Basilica in Vatican City.
Francis, 86, entered the church in a wheelchair, and sat at the site of the altar for most of the Mass on Saturday evening.
"While animals feed in their stalls, men and women in our world, in their hunger for wealth and power, consume even their neighbours, their mothers and sisters," he said.
He did not specifically mention the Russian-Ukraine war during the service.
During the early stages of Russia's full-scale invasion launched on 24 February, the Argentine pontiff was widely criticised in Ukraine for making what many Ukrainians saw as cautious comments, without blaming Russia directly.
In June, he suggested that the war was "somehow either provoked or not prevented".
But the Pope later denounced what he described as atrocities committed by Russian troops.
