By Philip Pullella
VATICAN CITY (Reuters) - Pope Francis leaves on Tuesday for a peace meeting of world religious leaders in Kazakhstan marked by the conspicuous absence of Russian Orthodox Patriarch Kirill, who supports the war in Ukraine.
Kirill had been expected to attend the Seventh Congress of Leaders of World and Traditional Religions, and Francis had several times said he was willing to talk to him.
Their meeting in Cuba in 2016 was the first between a pope and a Russian Orthodox patriarch since the Great Schism of 1054 divided Christianity into Eastern and Western branches.
But the Russian Church abruptly announced last month that Kirill would skip the meeting in the Kazak capital, Nur-Sultan. It gave no reason.
Some top Vatican officials were relieved that the encounter would not take place because of the bad optics of the pope meeting with a key backer of Russian President Vladimir Putin's invasion of Ukraine, according to a senior Vatican source.
Ukraine's ambassador to the Vatican, Andreii Kurash, also told the Vatican that his government would not look positively on a pope-patriarch meeting, preferring that the pope first visit Kyiv, according to the source.
Kirill has given enthusiastic backing to Russia's invasion of Ukraine, which the patriarch views as a bulwark against a West he calls decadent.
His stance has caused a rift with the Vatican and unleashed an internal rebellion that has led to the severing of ties by some local Orthodox Churches with the Russian Orthodox Church.
The Vatican has been trying to mend strained relations with Ukraine after the pope upset Kyiv last month by referring to Russian ultra-nationalist Darya Dugina, who was killed by a car bomb near Moscow, as an innocent victim of war.
Still, the war in Ukraine is likely to cast a long shadow on the meeting, which is due to be attended by more than 100 delegations from about 50 countries.
Speaking at his Sunday address, Francis called his Kazakhstan trip "a pilgrimage of dialogue and peace" and in the very next line asked for prayers for the Ukrainian people, who he often has said were being "martyred".
The logo of the trip is a dove carrying an olive branch.
There are only about 125,000 Catholics among the 19 million population of the vast Central Asian country, which is a former Soviet Republic. About 70% of the Kazakhs are Muslim and about 26% Orthodox Christians.
Francis, who uses a cane and a wheelchair because of a knee ailment, will say a Mass for the tiny Catholic community.
The religious leaders are due to hold a silent prayer at the start of the meeting on Wednesday and issue a joint statement at the end.
Francis is scheduled to hold private meetings with several religious leaders but the Vatican has not yet announced who they are.
(Reporting by Philip Pullella; Editing by Tomasz Janowski)