Top clerics from Orthodox countries converged on Ukraine on Friday for three days of festivities, deepening a longstanding dispute with Russia over the ex-Soviet state's right to its own independent church.
The celebrations to mark the 1,020th anniversary of the embrace of Orthodox Christianity in the region are certain to be overshadowed by the dispute between Kiev and Moscow which has long extended beyond religion into politics.
After mainly Orthodox Ukraine won independence from Soviet rule in 1991, a separate church was formed.
But it remains unrecognised by the world-wide Orthodox Church, which sees the Ukrainian branch of the Russian Orthodox church as its only representative in the country.
Authorities in Ukraine, site of the Kiev Rus state that preceded modern-day Ukraine and Russia, are hosting the event. Russian Patriarch Alexiy II is attending after securing an agreement that the independent Kiev-based church will stay away.
But its clerics still lobby for change.
"Ukraine has the right to its own church. Unfortunately, Moscow is denying this right in the same way it opposes the very notion of Ukraine as an independent state," Bishop Yevstratiy, a spokesman for the independent church, told Reuters.
"What is going on in Ukrainian Orthodoxy has nothing to do with violating church law. It is caused by Moscow fighting for power in Ukraine - economic, political and spiritual power."
Statistics show the churches have roughly the same number of parishioners. Property disputes between the two sides in the 1990s sparked street scuffles, often between elderly believers.
Pro-Western Ukrainian President Viktor Yushchenko, an ardent Orthodox believer, sees creation of an independent church as part of Ukraine's task of building a national identify.
HIGH PROFILE FOR PATRIARCH
The president has tried to boost the event's profile by focusing on the visit by Constantinople Patriarch Bartholomew, worldwide leader of more than 225 million believers in the Orthodox church - formed after the 1054 schism with Rome.
Bartholomew was met by Yushchenko and given top honours at Kiev airport on Friday, a military honour guard, goose-stepping soldiers and the playing of Ukraine's national anthem. Posters of the president alongside Bartholomew dotted Kiev streets.
Tens of thousands of guests will hold a Saturday prayer meeting near the 11th century St Sofia Cathedral and a Sunday service by the Dnieper River.
Russia is locked in disputes with Ukraine's pro-Western leaders on natural gas prices, their drive to join NATO and their calls for Russia to pull its Black Sea Fleet out of Ukraine's Crimea Peninsula by 2017.
In an indicator of tensions, Ukraine's ambassador to Moscow was summoned to the Russian foreign ministry and told the festivites were staged "with a lack of respect for the Russian Orthodox church and the feelings of millions of believers".
A ministry statement also complained about the decision by Ukrainian authorities to deny entry on Friday to a nationalist member of parliament and "endless talk" it said was disrupting negotiations over the future of the Black Sea fleet.
Proponents of the independent church have considered placing it under the jurisdiction of Constantinople - as an Orthodox church in Estonia did in the 1990s - to win recognition later.
The Moscow church says this will only lead to trouble.
"This is a revolutionary process and it won't work in the church," said Archimandrite Kiril, a spokesman for the Russian church. "We have started the process of rapprochement ... Now the intervention of political authorities could bring us back to the early 1990s with violence and conflicts."
