US F-35B aircraft conducted flight trials with HMS Queen Elizabeth last year (Picture: MOD).
A former head of the Royal Navy has raised concerns about the government's commitment to buying F-35B Lighting stealth jets.
Admiral Lord West says the Ministry of Defence should purchase enough of the necessary variant for both Queen Elizabeth class-carriers and to have an operational unit for training and repair.
American aircraft flown by British pilots landed on the deck of HMS Queen Elizabeth for the first time in September.
British jets will first land on the carrier's deck later this year.
The UK's F-35Bs arrived at their Marham home for the first time in 2018, with a further jets arriving in August.
Admiral Lord West said having fewer than 90 F-35B jets would cause problems.
The former First Sea Lord says any fewer than 90 jets causes problems:
"Well it leaves a hole in the carrier strike capability," he said.
The MOD has previously said it is committed to buying 138 aircraft.
Admiral Lord West also pointed to a recent interview by the Defence Secretary Gavin Williamson about plans to expand the the role of the Royal Navy.
"We'll have a base in the Gulf. We'll operate ships out in the Far East. You can only do that when you've got something like a carrier there to give you the support that's required."
The UK currently has 16 F-35B jets based at RAF Marham in Norfolk and in the United States, as well as two additional aircraft which are already on order.
Last November the Defence Secretary announced the UK is set to double the fleet by ordering 17 more aircraft.
The MOD said the jets will be jointly manned by the RAF and the Royal Navy and can operate from land and sea, forming part of a Carrier Strike Group when operating from the Queen Elizabeth-class aircraft carriers.