Nuclear submarine fire figures revealed
There have been 266 fires on nuclear submarines in the past 25 years, the Ministry of Defence has revealed.
The incidents included 74 on ballistic missile submarines. Three happened while the vessels were in naval bases; one of these was on a ballistic missile submarine.
SNP defence spokesman Angus Robertson said the "apparent vulnerability" to fire raised "grave questions".
The MoD said no fire had ever had an impact on nuclear safety.
Peter Luff, Minister for Defence Equipment, Support and Technology, gave the figures in response to a parliamentary question from Mr Robertson.
Of the 266 fires, 243 were classed as "small-scale" and categorised as a localised fire, such as a minor electrical fault creating smoke.
There were 20 medium-scale fires that were generally categorised as a localised fire, such as a failure of mechanical equipment creating smoke and flame, requiring the use of "significant onboard resources".
Mr Robertson said: "Any one of these fires could have had catastrophic consequences and the frequency of these incidents raises the most serious safety concerns.
"That so many of these incidents occurred on submarines that may have been nuclear armed is deeply troubling.
"Reports of a fire on a ballistic missiles submarine, while in port, must be addressed by the MoD - we need to know where this was.
"Beyond the obvious risk to the crew, citizens on shore, and the environment, a significant fire could severely limit the UK's ability to maintain a continuous at-sea deterrent.
"It makes a mockery of any UK claims to having a credible "independent" nuclear deterrent."
Information on whether ballistic missile submarines were armed with nuclear weapons when the fires occurred was not available, Mr Luff said.
Nuclear submarines are based at Faslane on the Clyde but the location of the incidents was not specified.
An MoD spokesman said: "No fire on board any Royal Navy submarine has ever had an impact on nuclear safety or the ability to operate a continuous at-sea deterrent.
"Due to the nature of submarine operations, meticulous records are kept of all incidents involving fire, however small.
"Most of those recorded were minor electrical faults that were dealt with quickly, safely and effectively.
"The Royal Navy operates a stringent safety regime on board all its submarines and all personnel receive regular and extensive fire safety training."