Pope Francis has revealed that he told the head of the Russian Orthodox Church to not be "Putin's altar boy".

Patriarch Kirill of Moscow has refused to condemn the invasion in Ukraine and has stood by Putin's actions.

The pope told Italian newspaper Corriere della Sera that he had a 40 minute meeting with Kirill in which he listened to the Orthodox leader explain why Putin was justified in his actions.

"During the first 20 minutes he held a piece of paper and read all the reasons for the war. I listened and said, 'I don't understand anything of this. Brother - we are not altar boys of the state. We must use the language of Jesus, not the language of politics'."

"The patriarch cannot turn himself into the altar boy of Putin,"

He added that they both agreed to cancel a planned meeting in Jerusalem in June.

Meanwhile, the Kremlin said on Wednesday that no agreement had been reached on a possible meeting between President Vladimir Putin and Pope Francis for talks about Ukraine.

Pope Francis said that he had asked for a meeting in Moscow with Putin to try to stop the war in Ukraine but had not received a reply.

He explained that he sent a message to Putin 20 days after Russia invaded Ukraine, asking for a meeting.

"Certainly it was necessary that the Kremlin leader opened a window," he said.

"We still haven't had a reply but we are still insisting, even though I fear Putin cannot and will not have a meeting at this time…but how can we stop so much brutality?"

While most world leaders have met with Ukrainian President Zelensky in Kyiv, the pope said he's chosen not to yet. "I must first go to Moscow, I must first meet Putin," he said.