London  - Britain's ageing fleet of Nimrod reconnaissance aircraft should be grounded because the planes have "never been airworthy," an inquest into a Nimrod crash in Afghanistan which killed 14 servicemen in 2006 ruled Friday.

"The entire Nimrod fleet has never been airworthy from the first time it was released to service nearly 40 years ago," judge Andrew Walker said at the end of the inquest at Oxford Coroner's Court.

His ruling, which is not binding on the government, brought an immediate response from the Ministry of Defence (MoD) which said that the 13-strong Nimrod fleet of Britain's Royal Air Force (RAF) was "safe."

Armed Forces Minister Bob Ainsworth insisted in a statement that the Nimrod was airworthy, and "that we are dealing with all the issues raised by this incident."

The 14 servicemen died when the plane exploded after air-to-air refuelling in Afghanistan in early September, 2006, in what was the biggest single loss of life suffered by the British military since the 1982 Falklands War.

Following the crash all air-to-air refuelling on the Nimrod fleet remains suspended. An earlier internal RAF report into the incident showed that ageing components and a lack of modern fire suppressants were among the "contributory factors" leading to the accident.

It said fuel probably escaped during the refuelling into a bay on the aircraft either because of a leaking fuel coupling or an overflowing fuel tank.

Analysts said Friday the Oxford verdict was a "huge embarrassment" for the MoD which considered the surveillance plane vital for Britain's deployment in Afghanistan.

Judge Walker said opportunities to spot the inherent dangers on the 37-year-old plane were missed and a design fault that led to the explosion went unnoticed.

After the internal RAF report Defence Secretary Des Browne apologized to the families of the victims, but at the inquest, relatives voiced their anger over the safety failures.

"We apologize again to the families, friends and colleagues of those who died for our failings which led to this tragic incident," Ainsworth said Friday.

But Andy Knight, the brother of one of the victims, said the apology was "an insult to the families." (dpa)