Image caption Farnborough is currently displaying a life-sized model of the F-35 aircraft

The F-35 combat jet, due to be used on the UK's new aircraft carriers, will not make its UK debut on the opening day of the Farnborough Airshow.

However, it may still appear later in the week, organisers have said.

Earlier this month, the entire fleet of F-35s was grounded in the US following an engine fire.

Plans for the jet to appear at the Royal International Air Tattoo in Fairford, Gloucestershire, last Friday were also cancelled.

"The aircraft is still awaiting US DoD (Department of Defense) clearance but we are hopeful that it will fly at the airshow by the end of the week," Farnborough organisers said in a statement.

The Pentagon's chief weapons buyer has blamed "excessive" rubbing of fan blades in the planes' engines for the fire, but said it was not a fundamental design flaw.

At a cost of about $400bn (£230bn), the F-35 family of jets is the most expensive defence project in US history.

Image copyright Lockheed Martin

The UK has invested heavily in the jet and some 500 British companies are involved in the project.

The initial UK order for 14 F-35Bs will, with support costs added, have a price tag of about £2.5bn.

BAE Systems has invested £150m in facilities that will build the rear part of the fuselage and tail fins.

BAE says it employs 2,000 "highly skilled" staff on the programme in the UK.

But the project, led by US-based Lockheed Martin, has been hit by repeated delays and cost overruns.

'Quite embarrassing'

Last week, the US Air Force and the US Navy grounded the aircraft, following an engine fire on one of the planes.

"If the F-35 doesn't make it to the show, it's quite embarrassing. It will jeopardise the timing of export orders," Richard Aboulafia, an analyst with Teal Group, said at the time.

"But assuming there's no major problems here, we aren't expecting a serious blow to the programme."

Last week, the Queen named one of the aircraft carriers due to carry the jets.

The RAF is taking the lead on bringing the jets into service, although each squadron of F-35B Lightning IIs will be joint with the Fleet Air Arm, with the first flight trials on board HMS Queen Elizabeth due in 2018.