Image copyright Lockheed Martin Image caption The F-35 is the world's most expensive weapons project

The Pentagon has said the F-35 combat jet - due to be used on the UK's new aircraft carriers - will not go to the Farnborough Airshow because of continuing inspections.

Farnborough organisers had initially said that while the jet would not appear on the opening day of the show, it might be shown later in the week.

The Pentagon's press secretary said it was a "difficult decision".

The F-35 has been grounded since last month due to an engine fire.

The announcement that the jet would not cross the Atlantic came at the same time the Pentagon announced it would resume test flights.

However, those flights would operate under restrictions which would make it difficult to carry out a long-distance flight.

One of the restrictions is that an engine fan must be inspected after three hours of flight - making a cross-Atlantic journey difficult.

"While we're disappointed that we're not going to be able to participate in the air show, we remain fully committed to the programme itself and look forward to future opportunities to showcase its capabilities to allies and to partners," said Navy Rear Admiral John Kirby.

The jet, whose manufacture is being led by Lockheed Martin, is the world's most expensive weapons project, costing approximately $400bn (£233bn).