British and French nuclear submarines collided earlier this month deep under the Atlantic in an event that could have sunk or released deadly radioactivity, it emerged on Sunday.
The British Royal Navy’s HMS Vanguard and the French Navy’s Le Triomphant are both nuclear powered and were carrying nuke missiles.
Between them they had around 250 sailors on board.
A senior Navy source said: “The potential consequences are unthinkable. It’s very unlikely there would have been a nuclear explosion.
“But a radioactive leak was a possibility. Worse, we could have lost the crew and warheads. That would have been a national disaster.”
The collision is believed to have taken place on February 3 or 4, in mid-Atlantic. Both subs were submerged and on separate missions.
As inquiries began, naval sources said it was a millions-to-one unlucky chance both subs were in the same patch of sea. Warships have sonar gear which locates submarines by sound waves.
But modern anti-sonar technology is so good it is possible neither boat “saw” the other.
A senior military source said: “The lines between London and Paris have been hot.”
The MoD insisted last night there had been no nuclear security breach. But this is the biggest embarrassment to the Navy since Iran captured 15 sailors in 2007. The naval source said: “Crashing a nuclear submarine is as serious as it gets.”