ROME, Italy (AFP) — Pope Francis, warned by doctors not to travel to Ukraine in the immediate future, will Tuesday bear a message of peace instead to a tense Central Asia with a three-day trip 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, will take part in an inter-religious summit in the capital, Nur-Sultan.

Francis departed from Rome's Fiumicino airport at 7:35 a.m. on an ITA Airways plane.

The 85-year-old said Sunday that the 38th trip abroad since his election in 2013 would be "an opportunity… to (have a) dialogue as brothers, animated by the common desire for peace, peace that our world is thirsty for."

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