The head of the Russian Orthodox Church, Patriarch Alexiy II, has died at the age of 79.
A spokesman for the Moscow Patriarchy said Patriarch Alexiy, who led the powerful church for 18 years and developed close ties with the Kremlin, died at his residence in Peredelkino, a former Soviet writers' colony, outside Moscow.
Russian president Dmitry Medvedev, who was on an official visit to India, hailed the patriarch as "an outstanding religious figure" and cancelled a planned trip to Italy to return to Moscow.
"He was a true shepherd, who throughout his life was an example of spiritual fortitude and noble human deeds," Mr Medvedev told state television. "He was always with his flock both in the days of reprisals and in the period of religious revival."
Prime minister and former president Vladimir Putin, an ex- communist spy who now openly professes his Orthodox faith, said Patriarch Alexiy was a "great statesman" who had "done a great deal for the establishment of a new Russian statehood".
The Church never commented on Patriach Alexiy's health and gave the cause of death as heart failure. But diplomats in Moscow had said the Patriarch had been suffering from cancer for some time.
In a sign of his importance, Russian state television immediately ran a film showing highlights from Patriach Alexiy's life, accompanied by the sound of tolling church bells.
Church officials said Metropolitan Juvenali of Krutitsy and Kolomna -- a senior bishop -- may lead the Russian Orthodox until the election of a new patriarch.
Patriarch of Moscow and All Russia since 1990, the Estonian-born Patriarch Alexiy was a powerful and influential figure with close links to the Kremlin but a controversial past and strongly held conservative views on social issues.
He oversaw a major religious revival in Russia after the collapse of the Soviet Union, with hundreds of new churches built across the country, monasteries reopened and seminaries filling with new priests.
But despite repeated church denials, he also failed to shake off allegations by researchers that he had links to the Soviet KGB intelligence service.
Russia's Orthodox Church is by far the biggest of the churches in the Eastern Orthodox communion, which split with Western Christianity in the Great Schism of 1054. It is the majority religion in Russia.
Patriarch Alexiy was outspoken in his defence of traditional Russian values and criticised the West over issues such as gay rights.
In a rare visit to western Europe in 2007, Patriarch Alexiy described homosexuals as sinners suffering an illness similar to kleptomaniacs and decried what he said was a rupture between morality and human rights.
Much of his reign coincided with the leadership of Polish-born Pope John Paul II at the Vatican.
After the fall of communism in 1989 and the break-up of the Soviet Union in 1991, relations between the Vatican and Russia's Orthodox Church were severely strained over accusations that Catholics were using their newfound freedom to poach souls.
The Vatican denied the accusations but the chill in relations was the main cause for the failure to arrange a meeting between PatriarchAlexiy and the Pope although they came close to arranging a meeting in a "neutral" venue, such as Vienna.
Reuters