Pope Benedict XVI has extended greetings to Orthodox Christians as they celebrate Christmas Eve on the Julian calendar.

The pontiff made his comment Friday to thousands of pilgrims gathered in Saint Peter's Square as Roman Catholics celebrated the feast of the Epiphany saying the light of Christianity continues to spread.

In Moscow, the head of the Russian Orthodox Church, Patriarch Alexy, urged believers to mark Christmas with good deeds.  Russia's Itar-Tass news agency says he urged the faithful to pool their efforts to allow the joy of Christmas to enter every home. Russia's Orthodox Church did not accept the "new" calendar introduced by Pope Gregory XII in 1582, and celebrates Christmas about two weeks later than most Christians.

Russian President Vladimir Putin attended a Christmas Eve service at a cathedral in the Siberian city of Yakutsk.

Some information for this story provided by AFP.