Orthodox leaders lead Sunday prayers in Turkey in show of unity

"From time to time clouds have temporarily overshadowed ties between the brethren churches," Bartholomew said after the prayer at St. George Church in Istanbul, addressing Kirill.

"These ... must immediately be sent to their places in the pages of history," Bartholomew, an ethnic Greek but a Turkish citizen, was quoted by the Associated Press as saying.

Relations between the churches have been strained in the past because churches in some former Soviet states, such as Estonia, have broken away from the Russian Orthodox Church and tried to pledge allegiance to Bartholomew instead.

The churches in Istanbul and Moscow, however, have recently pledged to overcome differences and achieve greater unity.

Kirill is also expected to hold talks with Prime Minister Tayyip Erdogan and President Abdullah Gul when he visits Ankara.

Kirill was elected in January as the successor to Moscow Patriarch Alexy II, who died in December.