Pope Francis has deplored Russia's annexation of Ukrainian territory and called on the Russian president to stop the war and on Ukraine's president to be open to talks.

"I deeply deplore the grave situation that has arisen in recent days, with further actions contrary to the principles of international law. It increases the risk of nuclear escalation, giving rise to fears of uncontrollable and catastrophic consequences worldwide," he said during the Angelus prayer.

He implored Russian President Vladimir Putin "to stop this spiral of violence and death" and on Ukrainian President Volodymyr Zelensky "to be open to serious proposals for peace".

He also urged the international community "to do everything possible to bring an end to the war, without allowing themselves to be drawn into dangerous escalations", and to support any efforts to resolve the conflict through dialogue.

It is the first time that the pontiff has directly addressed the Russian leader in a speech since the start of Moscow's invasion on 24 February.

Pope Francis has been trying since the start of the invasion to open a path of dialogue with Moscow, while condemning a "cruel and senseless war".

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Speaking two days after Mr Putin proclaimed the annexation of nearly a fifth of Ukraine and placed the regions under Russia's nuclear umbrella, Pope Francis also defended all countries' right to "sovereign and territorial integrity".

"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," Pope 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.

Kyiv and its Western allies have condemned Mr Putin's annexations as illegal, and Mr Zelensky has said his forces will continue their fight to recapture all Ukrainian territory occupied by Russian forces.