The Ministry of Defence has dismissed claims that a navy submarine was involved in the sinking of a French trawler off the Cornish coast.
The Bugaled Breizh was raised and returned to France
According to an investigation by French TV channel FR3 with a Paris magazine, the boat was sunk by HMS Turbulent.
The Bugaled Breizh sank off the Lizard with the loss of its crew of five on 15 January last year.
The programme said the submarine returned to Devonport naval base that night for repairs to its hull.
It was claimed that earlier in the day Turbulent had been taking part in an exercise off the Lizard.
HMS Turbulent: The navy says it was in dock
But a Royal Navy spokesman at Devonport said that while there had been a Nato exercise in the area, he insisted the submarine had been in the naval base throughout the day.
He said the nearest submarine at the time had been HMS Torbay, and that was about 100 miles away.
He said: "There is no question at all, HMS Turbulent was alongside in Devonport all day on the 15th.
"As the trawler sank on the 15th, the Turbulent could not have been involved in any way with the incident."
HMS Turbulent is one of five of the Royal Navy's seven Trafalgar Class hunter-killer boats based at Devonport.
A French lawyer representing the families of sailors who died on the Bugaled Breizh said he would be asking French magistrates to investigate the claims regarding HMS Turbulent.
Christian Bergot, said: "We have been completely unaware of this until now.
"It will be necessary to issue international letters to the British so that they give details on their position with regard to all these elements and so that they don't content themselves with denials."