The Royal Navy says it is investigating aft documents marked "official sensitive" were reportedly recovered successful a Wetherspoons pub toilet.
According to the Sun, the files carried details astir HMS Anson - 1 of the navy's astir precocious vessels.
The insubstantial says the files were near successful the Furness Railway pub successful Barrow-in-Furness, with a root saying they were recovered connected the level of a toilet cubicle.
The navy said they were "generic" papers with nary classified information.
In a statement, the Royal Navy spokesman: "These are generic grooming documents that transportation nary classified information.
"However, we instrumentality each information matters highly earnestly and volition analyse the circumstances of their discovery."
The BBC has not seen the documents.
HMS Anson is simply a nuclear-powered onslaught submarine, which was built astatine the BAE Systems' shipyard successful Barrow-in-Furness, successful Cumbria, precise adjacent to the pub wherever materials were found.
The 97m-long (318ft), 7,800 tonnes, nuclear-powered vas is the 5th of the caller Astute-class onslaught submarines to articulation the Navy fleet.
According to the Ministry of Defence, Astute-class submarines are "the largest, astir precocious and "most powerful" onslaught submarines ever operated by the Navy - and Anson is susceptible of circumnavigating the globe without resurfacing.
The hunter-killer vas is is present astatine His Majesty's Naval Base successful Clyde, Scotland.
A root told the Sun that the files were discovered connected the level of a cubicle connected what was "quite a lively night".