MURMANSK, Russia -- Russia's navy chief gave the firmest indication to date Monday that an explosion of one of the torpedoes on board the Kursk destroyed the nuclear submarine, killing all 118 men on board.

Russian Navy Chief Vladimir Kuroyedov told reporters that preliminary findings showed that the fuel used for the Kursk torpedoes was too volatile, sparking the initial fire that sank Russia's most modern submarine on August 12, 2000.

"The confidence of scientists, constructors and the navy leadership in the fuel which was used in the torpedoes was not justified," said Kuroyedov.

He added that the torpedoes on board the Kursk had first been developed in 1957 and were due to be imminently replaced.

"This type of torpedo was already decomissioned -- we were planning to get rid of them and looking to get them replaced," Kuroyedov said.

His comments suggest that Russia has now conceded that the Kursk did not sink following a collision with a NATO vessel, or was destroyed by a World War II mine left behind in the Barents sea.

However, the Russian government is yet to report its final findings on the disaster, which highlighted the state of disrepair of the country's once-mighty military force, AFP reported.