Pope Francis' peace envoy to Ukraine, Cardinal Matteo Zuppi, will visit Beijing this week, the Vatican said on Tuesday.

The trip from Wednesday to Friday "constitutes a further step in the mission desired by the Pope to support humanitarian initiatives and the search for paths that can lead to a just peace," the Vatican said in a brief statement.

It did not mention the war in Ukraine.

Zuppi, who is head of the Italian bishops' conference, was asked in May by the 86-year-old pope to lead a peace mission to try and stop the war.

The cardinal travelled to Kyiv in June, where he met President Volodymyr Zelensky. Three weeks later, he went to Moscow where he met the ombudswoman for children's rights Maria Lvova-Belova, who is wanted by the International Court of Human Rights for the illegal transfer of Ukrainian children to Russia. In July, Zuppi met with US President Joe Biden about Vatican humanitarian efforts in Ukraine.

Zuppi, 67, was elected head of the Italian Episcopal Conference last year, and hails from the Sant'Egidio Catholic Community, which specialises in diplomacy and peace efforts.

China has been Russia's key international ally but has also stepped up diplomacy with Ukraine. (AFP)