Fatal train crash caused by bomb, says Russia

A hidden bomb has been cited as the cause of an explosion which led to the derailment of a Russian train on the main line between Moscow and St Petersburg, Press TV reported.

A bomb equivalent to 7 kg of TNT was detonated based on preliminary findings, Press TV's correspondent Svetlana Korkina reported on Saturday.

According to Russia's Federal Security Service, a team of officers have been put together to investigate the bombing.

The latest death toll of the attack stands at 26 people dead, although different officials are putting the toll at different figures. Another 18 people are still missing and about 100 people have been injured.

Authorities confirmed the death of two high-ranking federal officials in the crash, added the Press TV correspondent.

About 27,000 passengers remained stranded in train stations because the accident interrupted normal train communications.

Russian President Dmitry Medvedev ordered several law-enforcement agencies to investigate the attack and help those affected.