For much of the Orthodox Christian world, Thursday is celebrated as Christmas Day. Believers in Russia, Ukraine, and parts of Eastern Europe and the Middle East flocked to churches for the holiday.

Some Orthodox churches follow the liturgical calendar observed by the Roman catholic and Protestant churches and celebrate Christmas on Dec. 25.

A look at Christmas events throughout the world Thursday:

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RUSSIA

As Christmas approached across the sprawling country's nine time zones, Russians flocked to churches for long and solemn Masses. At Moscow's enormous Christ The Savior Cathedral, the service began at 11 p.m. on Wednesday and stretched two and a half hours, led by Russian Orthodox Patriarch Kirill, with the devout standing shoulder-to-shoulder.

President Vladimir Putin attended a midnight service at a church in the village of Turginovo, about 150 kilometers (90 miles) northwest of Moscow, where his parents were baptized.

Soldiers taking part in Russia's airstrikes in Syria attended a nighttime service in a tent on the Russian air base. The tent's walls were lined with icons and a few strings of purple lights were festooned at its entrance.

In his Christmas greetings to the nation, Putin said: "It is very important in these days that the Russian Orthodox Church and other Christian confessions in Russia continue the traditions of responsible service, help people find belief and give them force in life. They participate actively in upbringing of the growing generations, in development of the institutes of family, maternity and childhood."

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EGYPT

Egypt's Coptic Orthodox Christians celebrated Christmas Eve across the mainly Muslim country amid tightened security for fear of militant attacks, which have exponentially increased following the military overthrow of an Islamist president.

Roadblocks were set up before churches nationwide and cars and motorcycles were temporarily banned from idling in front of them, police Maj. Gen. Gamal Halawa said. In Cairo alone, police searched over 300 churches for explosives.

Egypt's Orthodox Coptic Christians fervently supported the 2013 ouster of Islamist President Mohammed Morsi. Ever since, Christian homes, businesses and churches have been more targeted.

"We have been late in restoring and fixing what has been burned.... Everything will be fixed... Please accept our apologies for what happened," President Abdel-Fattah el-Sissi, who as military chief led Morsi's overthrow, told the crowd on Wednesday at Cairo's St. Mark Cathedral, the papal seat, in a rare public apology and acknowledgement of the attacks. Egyptian presidents never attended Christmas masses, making el-Sissi's visit this year, the second of its kind, doubly appreciated.

The heightened security measures were in part a preparation for the Jan. 25 anniversary of the 2011 uprising that toppled longtime autocrat Hosni Mubarak. Officials including el-Sissi have voiced concern about attempts to mark the anniversary of the revolt with protests in recent weeks.

Egypt's Orthodox Coptic Christians make up about 10 percent of the country's 90 million people.

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GEORGIA

In Tbilisi, the capital of Georgia, the main avenue was crowded with colorfully dressed marchers in the traditional Christmas Day procession, collecting gifts and goods to donate to the needy.

The tradition, called "Alilo" (Glory to God), dates back centuries, when people would go out to collect alms for charity after Christmas Mass. It was banned during Soviet times, and restored only in 2000.

The procession included people dressed in robes displaying Georgia's national emblem of a red cross on white background and others in outfits symbolizing scenes of the Nativity. Some rode in carts pulled by donkeys or cattle, and other carried animal mock-ups including a camel and giraffe.

"This procession is an attempt to share the happiness with all those people who could not celebrate Christmas because of illness or poverty. We will go to all of them and bring gifts," said Father Kakhaber Gogotishvili, a priest who took part

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UKRAINE

President Petro Poroshenko and his family attended Christmas services at a village church in the Ivano-Frankiivsk region in the foothills of the Carpathian Mountains. According to the presidential press service, Poroshenko and others prayed for peace and reconciliation "on all Ukrainian land."

Conflict between Ukrainian forces and Russian-backed rebels in eastern Ukraine persists, although the intensity has diminished in recent months. Rebels said on Wednesday that they were prepared to release some of the conflict's prisoners on Christmas, but Ukrainian authorities made no direct public response and there were reports Thursday of a release taking place.

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Nour Youssef in Cairo and Sophiko Megrelidze in Tbilisi contributed.