An explosion of fuel in an old torpedo caused the Kursk submarine to sink nearly two years ago, the government commission investigating the disaster has concluded.

After the first explosion everyone who was in the front section of the submarine died - the second explosion caused the destruction of the rest of the vessel Valery Dorogin Vice-Admiral

The submarine, one of Russia's largest and most advanced vessels, did not collide with a foreign ship or with a stray mine, as Russian officials had suggested shortly after the disaster in August 2000.

After a two-year inquiry, the commission instead blamed the use of hydrogen peroxide fuel in the submarine's torpedo, widely considered unstable.

The explosion of the fuel in the torpedo started a fire, which subsequently caused all ammunition on board to detonate, Vice-Admiral Valery Dorogin, a member of the commission, told the Interfax news agency.

All 118 men on board the submarine died in the disaster.

Out of action

"After the first explosion, everyone who was in the front section of the submarine died," said Vice Admiral Dorogin. "The second explosion caused the destruction of the rest of the vessel."

A note written by one of the sailors on board which was subsequently found in the wreckage showed that he and at least 20 other colleagues had headed to the back of the vessel, and had survived for several hours.

After the disaster, the Russian Navy ordered peroxide-fuelled torpedoes to be removed from service

Peroxide fuel had been a staple of the Russian Navy in the post Soviet-era because it was so cheap, but other countries have abandoned its use because it is thought too unstable.

Britain returned to other fuels after an accident on board HMS Sidon in 1955, when the craft was using peroxide fuel. Thirteen sailors died in the incident.