Pope Francis has urged Russian President Vladimir Putin to "stop this spiral of violence and death" in Ukraine and condemned the "absurd" risk to humanity of catastrophic nuclear war as tensions heighten.
The pontiff made his strongest plea yet on the seven-month war as he addressed the public in St Peter's Square in Vatican City.
It was the first time in public that he referenced Mr Putin's leadership.
He also called on Ukrainian President Volodymyr Zelensky to "be open" to serious peace proposals.
And he implored the international community to "use all diplomatic instruments" to end this "huge tragedy" and "horror" of war.
"This terrible, inconceivable wound of humanity, instead of shrinking, continues to bleed even more, threatening to spread," Pope Francis said.
"That humanity again finds itself before the threat of atomic war is absurd.
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"What more has to happen, how much more blood has to flow?" before the war ends, he asked.
He expressed anguish that "the world is learning about the geography of Ukraine" through the names of its cities and towns, now associated with the death of civilians, including Bucha and Mariupol.
Throughout the war, he has criticised the use of arms and urged dialogue, but recently he has stressed Ukraine's right to defend itself from aggression.