At least 170 people were killed, including 45 children, when the three-engine Tu-154 jet came down en route from a Black Sea resort to St. Petersburg in stormy weather 45 kilometers (30 miles) north of regional center Donetsk.
Thursday is a day of mourning in Russia with flags flying at half-mast and entertainment events and television programs cancelled.
All Orthodox churches in Russia's second city, which lost 133 residents in the crash, will hold services in line with instructions from Metropolitan Vladimir, St. Petersburg's chief cleric.
The city's principal church, Kazan Cathedral, which is dedicated to one of the most revered icons in the Russian Orthodox Church, will hold a service at 12:00 Moscow time (8:00 a.m. GMT).
Another service in St. Sophia's Cathedral in Tsarskoye Selo, a former residence of the imperial family near St. Petersburg, will take place the same time.
Catholics and Muslims will also attend commemorative services at churches and mosques.
"All Muslims in St. Petersburg will also be praying for the victims all day long at home," said Zhafyar Ponchayev, chief mufti of St. Petersburg and Russia's northwestern regions.
St. Petersburg's Jewish community said the clergy and believers in the Grand Choral Synagogue would offer prayers for the victims "asking God for heaven for their souls."
At least 125 relatives of those who died in the crash gathered earlier Thursday at the site of the tragedy, where a cross and stone have been placed in memory of the victims.
