Image copyright PA Image caption In July the Red Arrows flew over HMS Queen Elizabeth to mark the official naming of the vessel by the Queen

The Royal Navy may ask US squadrons to fly off its new aircraft carrier following delays to its new F35B fighters, BBC Newsnight has learned.

MoD insiders said the US Marine Corps would be offered the use of HMS Queen Elizabeth for flight operations.

The UK plans to have its first F35 squadron operational by 2018, but Newsnight has learned that there may be further delays.

The MoD said it was not aware of any further delay to the timetable.

The plan is for one squadron of British F35s to be ready for service at sea by 2021. But even if it is achieved, it will create a gap of years where the Queen Elizabeth is ready but British squadrons are not.

For the past year defence analysts had been expecting the MoD to order 14 of the new jets.

UK pilots

In February, Newsnight was told that it would be placed "within days". But persistent doubts about the F35's enormously complex software, and an engine fire this summer caused successive delays to the decision.

When the British purchase was announced, last month, it was for just four of the planes. The MoD says that this order will allow trials to start from the Queen Elizabeth on time with "UK F35Bs, flown by UK pilots".

But the slowdown in the expected purchasing rate is bound to delay the aircraft's entry into squadron service, say defence insiders.

Former chief of the defence staff General Lord Richards told Newsnight that asking US jets to fly from the Queen Elizabeth would be a sensible way of bridging the gap between the carrier being completed, and a British squadron of jets being available.

He said: "If we can catch up using American aircraft in the intervening period that would make good sense."

Image caption Gen Lord Richards became the chief of defence staff - the head of the British armed forces - in 2010

He denied that it was humiliating for Britain not to have its own jets ready when it comes into service because the ships could be used for different functions such as carrying helicopters or troops.

However, the MoD said on Wednesday that it was "not aware" of any further delay to the timetable for the first operational squadron.

Even if the timetable is kept, senior naval officers are nervous that a gap in capability during 2018-2021, coming at a time when the defence budget will come under fresh pressure after the next general election, could damage their chances of keeping the two new carriers, which they regard as central to remaining a "first division naval power".

With a Strategic Defence and Security Review (SDSR) expected to get under way in 2015, the huge ships, which have long been the subject of controversy in Whitehall, are likely to come under fresh scrutiny.

Newsnight has been told that many decisions relating to the new ships, including such questions as their communications fit, are now being put on hold until the SDSR. Naval chiefs are therefore determined to get them to sea with a credible looking complement of aircraft on their decks, as soon as possible.

An MoD spokesman said: "The Lightning II [F-35B] Force will be manned by Royal Navy and RAF pilots and we can be clear that aircraft used for the first Class Flying Trials in 2018 will be UK F35Bs, flown by UK pilots.

"We are also working closely with our key allies, specifically the US Marine Corps and the US Navy, to regenerate our carrier strike capability and we will seek further opportunities to do so in the future."