The Kursk, before its ill-fated exercise

But the LR5 was never used.

Mr Heron spoke to BBC Scotland as the rescue crew sailed back home from the wreck site in the Barents Sea.

He said: "We are both sad and bitterly disappointed that the job we came here to do was not permitted to be done by the Russians.

"At every turn they went out of their way to obstruct any arrangements.

"Any arrangement or proposed operation that they spoke about was rescinded, gone back on, altered or countermanded."

He said the British crew had been "revolted" to hear the Russians say that they had done everything they could to save those on board the submarine.

Rescuers were angered at their treatment

"We had one of the most sophisticated vessels available in Europe sitting at the wreck site with a submersible specifically designed to rescue men from submarines.

"The Russians would not let us use that."

He said the crew had lived in hope that the sailors were still alive until the very end.

Mr Heron accepted it was unlikely that there were any traces of life on the submarine by the time they arrived.

But he said: "If life was still extant, undoubtedly lives were then lost by the fact that we were sat doing nothing."

'Sham'

He thought the rescue crew's treatment had been down to Russian pride.

Mr Heron said the Russian navy was "a sham and a joke" - but that the country's people were being told something different.

Russian President Vladimir Putin has said on state television that he feels responsible and guilty for the submarine disaster, which cost the lives of 118 sailors.

Mr Putin said on Wednesday that an objective picture of the causes of the tragedy should be built up before anyone is blamed.