When a British nuclear submarine and a French one collided in the deep Atlantic Ocean earlier this month, crews on both vessels were initially puzzled and not sure what had happened.

“These submarines are undetectable, they make less noise than a shrimp,” Morin said, indicating that the utmost sense of secrecy made crews on the highly sophisticated vessels failed to be aware of the collision at the first stage.

Morin denied that the two vessels were hunting each other when collided, saying the commander on the French submarine thought the vessel hit something like a shipping container.

“Our submarine went back to Brest, the British submarine continued its patrol and it’s when we reported the incident that the British, who had just learned from their commander that there had been a problem, contacted us,” he said.

The collision between the two subs was not confirmed until the British side inspected the damage on the French vessel, Morin said.

The defense minister also denied that the French navy had intended to hide the incident from the public.

Despite being equipped with sonar to detect other vessels, neither submarine apparently realized the other was in the same part of the ocean.

Experts said submarines don’t always turn on their sonar systems, or make their presence obvious for the sake of being undetectable to enemies.

The accident, described by Anti-nuclear groups as the most severe one involving a nuclear submarine since the sinking of the Kursk in 2000, reminded of the risks posed by radioactive material-powered submarines equipped with nuclear weapons.

Morin pointed out that the accident may prompt France and Britain to consider coordinating nuclear sub routes, saying one of the solutions under joint efforts “would be to think about the patrol zones.”

However, anonymous French naval officials were quoted by AFP as telling that the nuclear missile fleet is separate from the already existing coordination of ordinary subs’ patrol zones, since the movements of nuclear ballistic submarines are national secrets and closer cooperation would be an extremely sensitive proposition.

The colliding submarines, both carrying atomic weapons, were Britain’s HMS Vanguard and France’s Le Triomphant. The crash damaged the submarines, but caused neither injuries nor damage to the vessels’ weapons.

HMS Vanguard, the oldest vessel in Britain’s four nuclear-armed submarines that carries the Trident nuclear missile, came into service in 1993. It has a crew of around 135 and typically carries16 Lockheed Trident D5 missiles.

Le Triomphant entered service in 1997. It carries 111 crew and about 16 nuclear missiles.

VietNamNet/Xinhuanet