Pope urges end to 'senseless' Ukraine war during Kazakhstan visit

Pope Francis appealed for peace and an end to the "senseless and tragic war" in Ukraine during the start of a three-day visit to Kazakhstan.

The Argentine pope, who is forced by knee pain to use a wheelchair and has admitted he must slow down or consider retirement, made the journey to participate in an inter-religious summit.

"I have come to echo the plea of all those who cry out for peace," Francis said during an address to diplomats and members of civil society.

"Now is the time to stop intensifying rivalries and reinforcing opposing blocs," he said, calling for a new "spirit of Helsinki", referring to 1975 accords that helped bring an end to the Cold War.

President Kassym-Jomart Tokayev said it was a "great honour" to welcome the 85-year-old pontiff on his arrival in the capital Nur-Sultan, his 38th trip abroad since his election in 2013.

Russian Orthodox Patriarch Kirill, a close ally of President Vladimir Putin, was initially expected but has pulled out of the September 14-15 event, dashing hopes of a meeting with Francis over the Ukraine conflict.

While the pope has called for peace and denounced a "cruel and senseless war", Kirill has defended Putin's "military operation" and the fight against Russia's "external and internal enemies".

About 100 delegations from 50 countries are expected to take part in the event in Kazakhstan, a former Soviet republic that gained independence in 1991.