AN INQUIRY into how two nuclear submarines, one British and one French, crashed into each other in the Atlantic Ocean was demanded by MPs last night.
The vessels, the Faslane-based HMS Vanguard and Le Triomphant, both believed to be carrying nuclear missiles, collided two weeks ago. Intelligence experts said that the crews might have been playing a game of cat and mouse when the incident happened.
The Ministry of Defence admitted the collision only yesterday, after it was confirmed by French officials, prompting one politician to accuse it of a "hush-hush attitude". The submarines – each nearly 500ft long – were both damaged in the underwater incident, thought to have happened on the night of 3-4 February.
Mike Critchley, a former Royal Navy officer and the publisher of Warship World magazine, said the collision in the Atlantic was a "one-in-a-million chance".
Mr Critchley also suggested that budget cuts might have left some Navy officers without enough practical experience.
He said: "The training is extensive, but whether the people who are in command of these major assets have considerable experience at sea is questionable, because the Navy has been seriously cut back in recent years.
"So the progression from a junior officer to a senior officer includes far more shore time than sea time. That is why, I would suggest, some accidents have happened in the past."
Disarmament campaigners described the incident – in the Atlantic's 41 million square miles – as a "nuclear nightmare of the highest order", which could have released "vast amounts of radiation".
Angus Robertson, the SNP's defence spokesman, said: "The MoD's hush-hush attitude appears to conflict with the French position.
"The MoD 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."
Nick Harvey, the Liberal Democrats' defence spokesman, called for an immediate internal inquiry, with "some" publication of its conclusions, in order to reassure the public. He said: "The people of Britain, France and the rest of the world need to be reassured that this can never happen again and that lessons are being learned."
The submarines may have been trying to track each other undetected – an activity that has continued since the Cold War, according to Bob Ayres, a former CIA and US army officer.
When such submarines came across similar vessels from other navies, they sought to get as close as possible without being detected, as part of routine training.
"They were playing games with each other – stalking each other under the sea," Mr Ayres said. "They were practising being able to kill the other guy's submarine before he could launch a missile."
He said several nuclear-armed United States and Soviet submarines had collided during the Cold War, but most of these incidents remained unreported.
Mr Ayres, a former associate fellow at Chatham House, the Royal Institute of International Affairs, said the submarines were not undetectable, despite their "stealth" technology.
Because of the sound of their nuclear reactors' water pumps, they were still noisier than old diesel-electric craft, which ran on batteries while submerged
He said the greatest danger in a collision was the hull being punctured and the vessel sinking, rather than a nuclear explosion.
But the Campaign for Nuclear Disarmament said it was the most severe incident involving a nuclear submarine since the sinking of Russia's Kursk in 2000. Kate Hudson, chairwoman, said: "This is a nuclear nightmare of the highest order.
"The collision of two submarines, both with nuclear reactors and nuclear weapons on board, could have released vast amounts of radiation and scattered scores of nuclear warheads across the seabed."
The French navy admitted on 6 February that Le Triomphant had hit "an immersed object, probably a container" while returning from patrol to its base near Brest in Brittany.
Yesterday, it confirmed the incident had involved another submarine, but said "the collision did not result in injuries among the crew and did not jeopardise nuclear security at any moment".
Despite this, the MoD initially declined to confirm the collision. But hours later, Admiral Sir Jonathon Band, the First Sea Lord, admitted: "Two submerged SSBN (Ship Submersible Ballistic Nuclear], one French and the other UK, were conducting routine national patrols in the Atlantic Ocean.
"Recently, the two submarines came into contact at very low speed. Both remained safe and no injuries occurred.
"We can confirm the capability remained unaffected and there has been no compromise to nuclear safety. HMS Vanguard returned safely to Faslane under her own power on 14 February."
The French submarine suffered damage to its sonar dome, suggesting that the Vanguard, which was dented and scraped, passed above it.
John Large, a nuclear consultant, said submarines tried to minimise the risk of being detected by switching off as much equipment as possible, such as sonar, which is used to track submerged objects, and relying instead on microphones He said: "They turn off everything they can and are covered in rubber tiles to absorb noise, but the one penalty is 'if they can't hear you, you can't hear them'."
He said the submarines' size meant even a low-speed collision would be a "big bump".
Mr Large said the risks caused by this included a fire on board which could lead to explosions and a radiation leak. "Each warhead has about 66-110lb (30-50kg] of high explosive around it," he said.
Lee Willett, of the Royal United Services Institute for Defence and Security Studies, in London, said the "freak occurrence" was in part due to the submarines' stealthy design.
"They are meant to be like holes in the water. It's not surprising that they couldn't hear each other."
CND dossier details toll of accidents
THE Scottish Campaign for Nuclear Disarmament has compiled a log of incidents involving Britain's nuclear submarines.
• JANUARY 1973: The Polaris-armed submarines HMS Revenge and HMS Repulse collided while manoeuvring at Faslane. The hydroplanes of Repulse were damaged.
• MAY 2000: Radiation leak on HMS Tireless in the Mediterranean. This resulted in a reactor repair in Gibraltar, which took a year.
• NOVEMBER 2000: HMS Victorious ran aground on Skelmorlie bank in the Clyde estuary.
• NOVEMBER 2002: HMS Trafalgar ran aground on Fladda-Chuain, north of Skye.
• MAY 2003: Tireless hit an iceberg while 200ft below the surface.
• MARCH 2007: Fatal explosion in Tireless under the Arctic icepack. Currently the subject of an inquest.
TOTAL subs per country (conventionally armed unless otherwise stated):
1 Bulgaria, Croatia, Portugal, Ukraine
2 Algeria, Equador, Indonesia, Malaysia, South Africa, Venezuela
3 Argentina, Israel
4 Brazil, Canada, Chile, Colombia, Egypt, Netherlands, Singapore, Taiwan, Spain
5 Poland, Sweden
6 Australia, Norway, Peru
10 France (4 nuke, 6 conventional), Germany, Italy
13 UK (4 nuke, 9 conv), South Korea
52 North Korea
70 USA (14 nuke, 56 conv)
90 China (5 nuke, 85 conv)
98 Russia (28 nuke, 70 conv)
PROFILE: HMS VANGUARD
Entered service: 1993
Displacement: 15,980 tons submerged
Length: 492ft (150 metres)
Top speed: 25 knots (29mph)
Maximum depth: c. 1,500ft
Nuclear missiles: 16
Missile range: 7,500 miles
PROFILE: LE TRIOMPHANT
Entered service: 1997
Based: L'Ile Longue, near Brest
Displacement: 14,335 tons submerged
Length: 453ft (138 metres)
Top speed: 25 knots (29mph)
Maximum depth: 1,640ft
Nuclear missiles: 16
Missile range: 3,750 miles