US jets could operate off the Royal Navy's new aircraft carrier before British planes are available for full strike operations.
The Ministry of Defence (MoD) said no offer had been made to allow US planes to use HMS Queen Elizabeth, but sources said letting their pilots fly from the vessel could help build up the experience of the ship's crew.
The first sea trials of the new F-35B planes in 2018 will involve British jets flown by British pilots, the MoD insisted, with the ability to launch air strikes from the carriers due by the end of 2020.
But the MoD said it was "working closely" with the US Marine Corps and US Navy to "regenerate our carrier strike capability".
BBC2's Newsnight programme reported that the US Marine Corps would be offered the use of HMS Queen Elizabeth for flight operations.
The programme also reported that there could be further delays in the timetable for the UK's F-35B programme, which is denied by the MoD.
An MoD source said no US offer had been "made or requested", but if one was made it would be to help improve flight control skills during the period of operational trials before the initial operating capability of full carrier strike.
It was not a case of "shunting off British jets to fly American ones", the source said.
HMS Queen Elizabeth is due to be handed over to the Royal Navy in 2017, with F-35B Lightning II jets beginning trials the following year.
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."
A MoD spokesman said: "The Lightning II Force will be manned by Royal Navy and RAF pilots and we can be clear that aircraft used for the first of class flying trials in 2018 will be UK F-35Bs, 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."
Shadow defence secretary Vernon Coaker said: "This fiasco is a direct result of the Tory Government's botched defence decisions.
"In 2010, against all advice, David Cameron switched the type of aircraft to be flown off the carrier from F-35B to F-35C, only to change his mind back again two years later.
"That wasted millions of taxpayer pounds and caused this delay in the delivery of aircraft for the Queen Elizabeth carrier.
"We welcome the co-operation of our US allies in making up for the Tory Government's shortfall. But there is no substitute for British-owned aircraft flying off a British-operated aircraft carrier."