The head of the Russian Orthodox Church, Patriarch Alexy II, who restored the authority of the church after decades of Soviet repression, has died, church officials say.

"Yes, he has died," a church spokesman said by telephone after Russian news agencies said the patriarch, aged 79, died earlier on Friday at his residence outside Moscow. There was no immediate word on the cause of death.

Born Alexei Ridiger, Alexy II made his ecclesiastical career at a time when the church was controlled by Soviet authorities before forging an alliance with the new Russian state under presidents Boris Yeltsin and Vladimir Putin.

The patriarch was an impressive character with a benign expression and moral authority among millions of Russian believers, but his personality was always locked in by the deeply hierarchical nature of his role.

Alexy II took stances on foreign policy issues that often matched the Kremlin line, criticising NATO strikes against Yugoslavia, the US-led war in Iraq and defending the rights of ethnic-Russians in the former Soviet Union.