The UK Royal Navy has just one nuclear powered submarine in operation after the rest of the fleet has been left out of action due to defects and damage, Daily Mail reported.

Four of the Royal Navy's new multi-billion hunter and killer submarines are still in dock at Barrow-in-Furness because of defects that have delayed their production - 15 years after the new ships were first ordered.

Only two of the boats have actively joined the fleet, and one has already had to return to the dock and can only be used for training after more than 50 defects were found.