MOSCOW, December 5 (RIA Novosti) - Patriarch Alexy II, who led the Russian Orthodox Church for 18 years, died at the age of 79 in his residency near the Russian capital on Friday morning, the Moscow Patriarchy said. (Russian Orthodox leader Alexy II dies at 79 - Image Galleries)
A senior church official said heart failure was believed to be the cause of death. The patriarch was known to have suffered from health problems in recent years.
Alexy II became patriarch of the Russian Orthodox Church, now the world's largest, in 1990, shortly before the collapse of the atheist Soviet Union, and presided over a religious revival in Russia, with thousands of churches and monasteries being restored and hundreds of new ones built across the country.
Under his leadership, Russia's last tsar, Nicholas II, and his family shot by the Bolsheviks in 1918, were canonized as well as many New Martyrs who suffered under communism.
Alexy II openly objected to then Pope John Paul II's visit to Russia, accusing the Catholic Church of attempts to poach converts in Russia and neighboring Ukraine.
In 2007, he signed a reunification act with Metropolitan Laurus, head of the Russian Orthodox Church Outside of Russia (ROCOR), after almost 90 years of separation. The foreign branch broke away in 1921, after accusing fellow clergymen in Soviet Russia of collaboration with the country's communist regime.
Alexy II voiced his open support for fellow Orthodox Serbs during the Kosovo conflict and called the declaration of independence by the Albanian province "an anti-historic event."
Alexy II also sought closer contacts with political leaders. The country's leadership, including Vladimir Putin and Dmitry Medvedev, attended church ceremonies led by the patriarch in Moscow's main cathedral.
Following news of the death, President Medvedev postponed a visit to Italy, due to have started on Saturday, and will return to Moscow from India later on Friday, the Kremlin said.
"The rise of the Russian Orthodox Church, the real establishment of the principles of freedom of conscience and faith are directly connected with him and his name," the Kremlin quoted Medvedev as saying.
Speaking in Armenia, Prime Minister Putin said: "He was a fair man, his death is an enormous loss, a tragic event."
In a statement on the patriarch's death, the Vatican said Alexy II had led the Russian church at a time of great change, and his leadership had helped the church withstand the hardships of post-Soviet transition.
Alexy II suffered a severe stroke in 2002. In April 2007, media reports said he was in a Swiss clinic in a serious condition or even dead. Church officials then confirmed the patriarch had undergone medical treatment in Switzerland, but denied the condition was serious.
On Thursday evening, Alexy II held a church service in one of Moscow's central cathedrals to mark a major religious holiday.
The church's ruling body, the Holy Synod, is due to gather for an urgent meeting in Moscow on Saturday to pick an acting leader and make arrangements for the funeral, Bishop Mark, deputy head of the patriarchy's foreign relations department said.
The patriarch, Alexei Rediger, was born on February 23, 1929, in the Estonian capital, Tallinn, into the family of a Russian Orthodox priest of German descent. He became a priest in 1950.