A Royal Navy nuclear-powered submarine that hit a rock last month in the Red Sea, damaging its sonar equipment, has returned to Britain, the Ministry of Defence said on Saturday.

After hitting a submerged pinnacle after passing through the Suez Canal, HMS Superb underwent repairs at the NATO facility in Souda Bay, Crete, before returning to Devonport naval base in Plymouth under its own power.

An assessment will now be made before a decision is made on the future of the 272ft long Swiftsure-class attack submarine that was about 80 miles south of Suez when it struck the rock.

No other vessel was involved and an investigation is now being carried out into the incident by the Royal Navy.

It is not the first time a Royal Navy vessel has run aground.

A recent report described how the nuclear-powered submarine HMS Trafalgar struck the bottom of the sea at more than 14 knots off the Isle of Skye in 2002 after basic navigational errors during a training exercise.

The destroyer HMS Nottingham hit rocks off the Australian coast, also in 2002, smashing open its hull, while two years earlier, the frigate HMS Grafton ran aground after striking rocks off the coast of Norway.