Mr Gerashchenko is a well-connected Ukrainian politician but some of his claims have proven to be unsubstantiated in the past.

The Kremlin has not commented on any loss of life. Neither the Black Sea fleet, nor local officials in Sevastopol have mentioned casualties.

Kursk similarities

The official hush around the sinking of the Moskva has drawn comparisons with the Kremlin’s silence after the Kursk submarine disaster in August 2000, a major scandal for the newly appointed president Putin.

The nuclear submarine sank during exercises in the Barents Sea above Russia’s Arctic Circle after a torpedo on board exploded in its hatch.

Most of the 118-strong crew were killed instantly, but some 23 sailors stayed in the half-flooded section and waited for a rescue that never came.

It took Mr Putin, still in his first year in office, several days before he ended his seaside vacation and went to the scene.

It later transpired that Russia had refused international offers of help, and it was only nine years later that a team of British and Norwegian divers were able to access the Kursk to find the bodies.

But in 2000, Mr Putin faced a massive outpouring of grief and anger from the sailors’ widows. Russia media, unencumbered by censorship, was scathing of his handling of the disaster.

He deflected the blame on the military’s post-Soviet decline and lashed out at the media for criticising him.

His popularity ratings markedly declined following the Kursk disaster, prompting him to clamp down on then-powerful independent TV channels.

This time, with critical media almost non-existent and opponents of Mr Putin in jail, such a response seems unlikely.