UK newspaper The Sun has reported that a British nuclear submarine has been in a collision with a French counterpart in the middle of the Atlantic Ocean.

Britain's HMS Vanguard and France's Le Triomphant are believed to have crashed into each other nearly two weeks ago, on February 3 or 4, but only now has the incident been made public.

Both submarines were carrying nuclear weapons.

The British submarine, which received several knocks to the hull, was dragged to the port of Faslane in Scotland. The French submarine had a badly damaged sonar sphere, but managed to return to the port of Brest under its own power.

Both submarines had about 250 sailors aboard.

The British Ministry of Defence has refused to comment but says nuclear security has not been breached and no radiation leakage occurred.