* Twenty-five people killed in train derailment
* Church head condemns "shameful, terrible" bombers
* Risk of greater tension between Christians, Muslims
By Conor Humphries
MOSCOW, Nov 29 The head of Russia's Orthodox Church on Sunday called on authorities to give a "powerful reply" to the people behind a train bombing that killed 25 people, as police probed whether Islamist rebels were involved. [ID:nGEE5AR00F]
A blast derailed a high-speed Russian train on Friday night on the main line between Moscow and Russia's second city, St Petersburg, raising fears of a new wave of attacks five years after a bombing campaign in Moscow by Chechen rebels.
"We believe the reply will be effective and powerful enough to show these shameful, terrible people that ... when the hand of an enemy is lifted against our lives, we are able to defend our citizens," Patriarch Kirill said at a memorial service in Moscow.
The comments were the strongest statement of anger against the perpetrators by a senior public figure. President Dmitry Medvedev on Saturday called for calm and ordered officials to do everything to help the victims of the attack.
No one has claimed responsibility for the blast, but security analysts said militant groups from Russia's mainly Muslim North Caucasus were the most likely culprits. [ID:nGEE5AS0D3]
A claim of responsibility by Islamist rebels could heighten tensions between Russia's Christian majority and its Muslim minority weeks after an Orthodox priest who was critical of Islam was shot dead in his church. [ID:nLK319219]
Russian investigators on Sunday combed the site of the blast and questioned residents of the rural area where it happened. The Emergency Ministry said 25 people were confirmed dead.
Passenger services resumed on the track on Sunday, with commuter trains rolling past an overturned carriage disguised by a green camouflage net, television pictures showed.
Television stations cancelled entertainment shows on Sunday and football matches observed a minute of silence.
((For a TIMELINE of major attacks in Russia click on [ID:nL01426901]))
(Writing by Conor Humphries; Editing by Robin Pomeroy) ((firstname.lastname@example.org; +7495-7751242))