ATHENS, Greece (AP) — The leaders of the world's Orthodox Christian churches have gathered on the Greek island of Crete for a landmark meeting, despite a boycott by the Russian church — the most populous in a religion of some 300 million people.

Ecumenical Patriarch Bartholomew led prayers attended by other church leaders Sunday on the eve of the weeklong summit held following decades of preparation.

Patriarch Kirill of Moscow and leaders of two allied churches are not attending the meetings, arguing that preparation had been inadequate. In a statement Friday, Kirill said he hoped religious leaders gathered in Crete could prepare for a full meeting at a later date.

Kirill visited Greece last month, joining Russian President Vladimir Putin on a trip to the monastic sanctuary of Mount Athos.