The families of 14 servicemen who died when an RAF spy plane crashed in Afghanistan are set to sue the Government.

A writ will be served on Defence Secretary Des Browne, accusing the Ministry of Defence of negligence, failing to minimise risk and a breach of the right to life in relation to the mid-air accident.

It will be the first time the department has faced a legal challenge under the European Convention of Human Rights.

If successful it could open the way for other families to sue the Government over the death of loved ones in Iraq or Afghanistan.

The action is being brought by the families of Sergeant Ben Knight, 25, and Flight Lieutenant Steven Swarbrick, 28 - both of whom died in the accident.

Ben's father Graham Knight said today was the last chance for the families to launch the bid, as it had to be carried out within two years of the accident - Tuesday is the second anniversary of the disaster.

Mr Knight said his main motivation was to see someone accept responsibility for the crash of the Nimrod jet.

"Nobody has been held accountable for the actual crash," he said.

"The Government has stood up and said we are sorry. The coroner has said the aircraft was never airworthy but nobody in the RAF or MoD has ever been held accountable for it."

Mr Knight, 56, said he was "disappointed", adding: "My son was proud to be in the RAF and I thought it was full of honourable men. But no one would stand up and take responsibility or resign."

The Nimrod spy plane exploded on September 2, 2006, just minutes after undergoing air-to-air refuelling.

The cause of the blast was fuel leaking into a dry bay and igniting on contact with a hot air pipe.

Earlier this year, a coroner ruled that the entire RAF fleet of Nimrod aircraft should be grounded.

Assistant Deputy Coroner for Oxford Andrew Walker said: "The aircraft was in my judgment never airworthy from the first release to service in 1969."

But the Government refused to agree with the recommendation that the entire fleet be grounded and that new procedures meant the aircraft was "safe to fly".

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