Russia train crash 'caused by bomb'

A bomb blast caused the derailment of a Russian express train, killing at least 26 people, intelligence officials say.

The Nevsky Express derailed in remote countryside on Friday night as the train travelled between the capital Moscow and St Petersburg.

Investigators found "elements of an explosive device" at the scene, the Russia's federal investigative committee said in a statement.

A senior intelligence official said a bomb had derailed the locomotive.

Alexander Bortnikov, head of Russia's domestic intelligence service told Russian President Dmitry Medvedev that a bomb equivalent to seven kilos (15 lb) of TNT had been detonated, Reuters reported.

There was no immediate confirmed claim of responsibility for the attack.

Russia's prosecutor-general has opened a criminal case on terrorism charges, Russian news agencies report.

Hundreds of rescuers and officials worked throughout the night at the scene near the town of Bologoye in Tver region.

Some reports say that as many as 39 people have died.

The train was carrying more than 650 people. More than 90 are in hospital, some of them taken there by helicopter.

Some passengers reported a loud bang occurring just before the derailment.