The submarines "were conducting routine … patrols in the Atlantic Ocean,” Britain’s First Sea Lord Admiral Sir Jonathon Band told reporters. “The submarines came into contact at very low speed. No injuries occurred. There was no compromise to nuclear safety."

Band’s statement confirmed media reports of the incident involving Britain’s HMS Vanguard and France’s Le Triomphant.

The French defense ministry, which had initially reported a collision between Le Triomphant and an unidentified object, also confirmed that the incident involved the British nuclear submarine while both vessels were conducting "routine patrols in the Atlantic."

"This is the first incident of its kind in more than 400 patrols that we have carried out," said Captain Jerome Erulin, a spokesman for the French navy.

The collision occurred in the early hours of February 4, British media reported, adding that both vessels were damaged in the crash. There were no reports of damage to the nuclear parts.

The British sub has now been towed to its Faslane base in western Scotland for repair, according to The Sun and The Daily Telegraph newspapers.

The two submarines are equipped with sonar to detect other vessels. Both vessels — between them carrying about 250 sailors — were reportedly submerged and on separate missions when they crashed.

France’s defense ministry initially said on February 6 that Le Triomphant, a ballistic nuclear submarine, was damaged when it hit an object under water earlier that week, but it did not identify what it struck.

Le Triomphant, one of France’s four nuclear-armed submarines, hit the object — said at the time to be probably a container — while submerging, and immediately returned to base at Ile-Longue, near Brest in northwest France.

"The sonar dome situated in the front was damaged," said a statement from the navy at the time, adding that the incident "did not result in injuries among the crew and did not jeopardize nuclear security at any moment."

Each vessel is 150 meters long and 13 meters in diameter, and can carry up to 48 nuclear warheads on a maximum of 16 missiles.

The BBC, which also reported the collision, said the vessels were both "seriously armed."

HMS Vanguard, launched in 1992, is one of four nuclear submarines operated by the British military as part of its Trident system. One is always on deterrent patrol.

France and Britain are two of the world’s five declared nuclear powers, along with the United States, China and Russia.

France has maintained a sea-based nuclear deterrent force since 1971. Britain is planning to renew its Trident submarine nuclear missile system at a cost of about 20 billion pounds (now 30 billion dollars, 22 billion euros).

Angus Robertson, the Scottish National Party’s leader in Britain’s House of Commons, demanded a government statement.

"The UK Ministry of Defense needs to explain how it is possible for a submarine carrying weapons of mass destruction to collide with another submarine carrying weapons of mass destruction in the middle of the world’s second-largest ocean," he said. "The MoD cannot hide behind operational secrecy and must make a statement on this as a priority."

Robin Millard/AFP/Expatica