THE stricken Russian nuclear submarine was blown apart by two explosions, the second registering 3.5 on the earthquake Richter Scale, it was revealed last night.

The huge second blast - equivalent to two tons of TNT - ripped a massive hole in the 118-man Kursk.

The first explosion was picked up on seismic machines in Norway at 7.28am last Saturday. It was followed two minutes later by the much bigger blast.

Western experts believe the sub sank like a stone after at least one of its torpedoes exploded. Russian president Vladimir Putin last night admitted there was no real hope of finding survivors - and there never had been.

Video footage of the sub, trapped 350ft down in the Barents Sea, yesterday revealed its conning tower had been blown to pieces and the hull split open from end to end. Russian officials claimed the 14,000-ton Kursk hit a "huge, heavy object" 20 metres below the surface, but failed to explain how a sub with state-of-the-art radar could suffer such a devastating collision.

A Russian rescue capsule finally reached the Kursk yesterday, but could not lock on to its hatches because it is tilting so badly.

Hopes of saving any survivors now depend on a British mission involving the hi-tech LR5 sub, due to arrive today. A 33-strong team including divers, medics and engineers will be joined by Russians.

Mr Putin said his defence chiefs told him last weekend that the chances of a rescue were "extremely small." The president - under fire for continuing his holiday - now faces a massive backlash in Russia.