The F-35 fighter jet has been cleared to fly after an investigation into the cause of a fire on one of the aircraft.

The Pentagon said the stealth aircraft's US fleet now has "limited flight clearance".

The F-35 Lightning II programme has been beset by problems. Aircraft have been grounded on a number of occasions and it is running wildly over budget.

Different versions are being built by Lockheed Martin for the US Marines, US Air Force and US Navy.

The UK is investing billions of pounds and staking the reputation of the military on the eventual success of the F-35 programme. 

A modified version of the jet - which can take off on a short runway and land vertically - will fly off the new Queen Elizabeth aircraft carrier, though the British government has yet to announce how many aircraft it will buy in the first tranche.

The Pentagon said it was not yet clear if any F-35 will take part in Britain's Farnborough air show, which is currently under way. 

The aircraft had been due to fly at the show in Hampshire on Monday, after failing to make the Royal International Air Tattoo in Fairford, Gloucestershire, on Friday.

The jets were grounded after a June 23 fire on an Air Force F-35A jet at Eglin Air Force Base in Florida.

The fire, in which the pilot was not injured, happened shortly before take-off. 

The incident was the latest to hit the Pentagon's costliest weapons project, the $398.6bn (£232bn) Joint Strike Fighter programme.

It followed an in-flight oil leak that triggered mandatory fleet-wide inspections of the jets last month.

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