Russian rescuers worked through the night to pull victims from the mangled steel of train carriages after it derailed at 9:30 Friday night.

The death toll is rising and at least 100 are injured.  

Authorities suspect the crash was caused by a bomb.

A criminal case has been opened on charges of terrorism and possession of explosives.

Head of Russia's National Railway could not speculate as to the motive of the suspected attack.

[Vladimir Yakunin, Head, Russian National Railway]:
"What I can say now is that the possibility of an explosion is also being investigated. As you know there are objective reasons to believe there was one, but the investigation will determine this."

Carrying 661 passengers from Moscow to St Petersburg, the train crashed near the village of Uglovka, some 200 miles north of the capital.

It's Russia's worst train accident in years and has raised fears of surge in attacks on the heartland by rebels from the North Caucusus.

Two-and-a-half years ago, a blast on the same line injured at least 30 people. Two people from Ingushetia were charged with that attack.