A nuclear-powered Royal Navy submarine has been forced into port in Gibraltar after a collision with a merchant vessel.
An immediate investigation has been launched after HMS Ambush was involved in the “glancing” collision while submerged off the coast of Gibraltar, the Royal Navy said.
The Astute-class vessel suffered “some external damage” but no crew members were injured in the incident.
The attack submarine’s nuclear reactor was undamaged, the Royal Navy said.
A statement posted yesterday on the Ministry of Defence website said: “At approximately 1.30pm local time today, HMS Ambush, an Astute-class submarine, while submerged and conducting a training exercise was involved in a glancing collision with a merchant vessel off the coast of Gibraltar.
“We are in contact with the merchant vessel and initial indications are that it has not sustained damage.
“The submarine suffered some external damage but there is absolutely no damage to her nuclear plant and no member of the ship’s company was injured in the incident.
“An immediate investigation is being conducted.”
It is the latest incident involving Britain’s most advanced attack submarine fleet.
HMS Astute, the first and lead vessel of a planned seven nuclear-powered Astute Class submarines, ran aground near the Isle of Skye off western Scotland in 2010.
The incident, which was caught on camera, happened during sea trials and saw it become stuck near the Skye bridge on October 22 2010. It was marooned for several hours, and was also damaged in a collision with a tug, the Anglian Prince, which tried to free it.
Its then commander, Andy Coles, was later removed from being in charge of the vessel.
The following year, an officer was killed on board the same submarine by a member of the crew.
Lieutenant Commander Ian Molyneux, 36, from Wigan, was killed by Able Seaman Ryan Donovan while Astute was docked in Southampton.
Lt Cdr Molyneux was awarded a posthumous George Medal - which is second only to the George Cross - for attempting to tackle drunken guard Donovan as he ran amok with an assault rifle during a civic visit by Southampton’s mayor. Schoolchildren had just left when Donovan started firing.
He admitted murdering Lt Cdr Molyneux and was jailed for life at Winchester Crown Court in September 2011.
The Astute class vessels are the most powerful attack submarines ever operated by the Royal Navy.
They weigh around 7,400 tonnes, equivalent to nearly 1,000 double-decker buses, and are 328ft (100m) long.
Armed with Tomahawk cruise missiles, the billion-pound, Barrow-built vessels can accurately strike targets up to 1,200 miles (1,931km) from the coast.
Advanced stealth technology means they can remain undetected despite being 50% larger than the Trafalgar Class submarines they will replace.
Their nuclear reactors will not need refuelling in their entire 25-year life and they make their own air and water, enabling them to circumnavigate the globe without needing to surface.