The war in Ukraine involves "imperial interests", with the world's "great powers" fighting there, Pope Francis said in extracts of an interview published on Friday.

Speaking to Swiss television RSI, the pontiff described how he had offered to go to Moscow to negotiate peace, but had been rebuffed.

"(President Vladimir) Putin knows that I am available," he said, according to a transcript published by RSI, ahead of the interview's broadcast on Sunday.

"But there are imperial interests there, not just of the Russian empire, but of the empires of other sides. It's typical of empires to put nations in second place."

The Argentine pontiff has repeatedly called for peace in Ukraine, although he was criticised in the first months after Russia's invasion for not blaming Moscow explicitly.

In the interview, Francis repeated his assessment that the conflicts around the globe currently amounted to a third "world war".

"The great powers are all involved. The battlefield is Ukraine. Everyone is fighting there," he said.