Pope Francis for the first time directly begged Russian President Vladimir Putin to stop the "spiral of violence and death" in Ukraine, saying on Sunday that the crisis was risking a nuclear escalation with uncontrollable global consequences.
In an address dedicated to Ukraine and made to thousands of people in St. Peter's Square, Francis also condemned Putin's latest annexation of parts of Ukraine as being against international law. He urged Putin to think of his own people in the event of an escalation.
One Vatican official said the impassioned address was so sombre it was reminiscent of a radio peace appeal by Pope John XXIII in 1962 during the Cuban Missile Crisis.
It was the first time Francis, who has often condemned Russia's invasion of Ukraine and the death and destruction it has caused, had made such a direct personal appeal to Putin.
Saying he was haunted by "rivers of blood and tears that have been spilled in these months," Francis also called on Ukrainian President Volodymyr Zelensky to be open to any "serious peace proposal".
He was making an urgent appeal "in the name of God" for an end to the conflict and said it was "absurd" that the world was risking a nuclear conflict.
"My appeal goes above all to the president of the Russian Federation, begging him to stop this spiral of violence and death, even out of love for his own people," Francis said.
"On the other side, pained by the enormous suffering of the Ukrainian population following the aggression it suffered, I address an equally hopeful appeal to the president of Ukraine to be open to a serious peace proposal," he said.
Francis later tweeted both the appeals to the two leaders in Russian and Ukrainian.
Speaking two days after Putin proclaimed the annexation of nearly a fifth of Ukraine and placed the regions under Russia's nuclear umbrella, Francis also emphasised all countries' right to "sovereign and territorial integrity".
Kyiv and its Western allies have condemned Putin's annexations as illegal, and Zelensky has said his forces will continue their fight to recapture all Ukrainian territory occupied by Russian forces.
Ukraine on Sunday claimed full control of the eastern logistics hub of Lyman, Kyiv's most significant battlefield gain in weeks.
"I strongly deplore the grave situation that has been created in the last few days, with more actions that are contrary to the principles of international law," he said in a clear reference to the annexation.
"This, in fact, increases the risk of an nuclear escalation to the point of fearing uncontrollable and catastrophic consequences on a global level," he said.
In a reference to ethnic Russians living in Ukraine, Francis said it was also necessary to respect "the rights of minorities and (their) legitimate worries".
Francis said it was "anguishing" that the world was learning about Ukrainian geography through names of places such as Bucha, Irpin, Mariupol, Izium, Zaporizhzhia and other places where people had suffered "indescribable suffering and fear".