The UK is in talks to cut the controversial Boeing contract for early-warning radar jets following concerns that British business was unfairly overlooked.
It is understood that the Ministry of Defence entered into negotiations with Boeing in the summer in order to secure better value for money for the E-7 Wedgetail jets programme.
One option under consideration is to reduce the contract with Boeing from five to three E-7 Wedgetails, in a move that is anticipated would save hundreds of millions of pounds over the next decade.
In March last year the MoD signed a fixed-price contract with Boeing for five E-7's in a £2bn plus-deal.
At the time of the announcement rival defence companies were furious that the contract was not opened to competition.
Douglas Barrie, a military aerospace expert at defence think-tank IISS, said: “Reducing the number to three looks like simple financial expediency.
“However, it’s really difficult to see how that number would provide the required coverage as five E-7 Wedgetails were seen as the baseline number of aircraft to give that.”
At any time it would mean one aircraft would be in maintenance, another used for training, with a third actually in theatre, meaning that any problems could create gaps in surveillance coverage.
Mr Barrie added: “Three E-7’s would mean coverage is sub-optimal and Russian air activity is only increasing and we are seeing more incursions than in a long-long time.”
Tobias Ellwood, chairman of the Defence Select Committee, stressed the need for five jets.
“It raises questions that this is a cart before the horse by reducing a high star capability that will help protect our F-35s before we know how they will be utilised.”
Defence sources said that while the MoD has asked for the order to be reduced to three Boeing is working on a “solution” that would be an order for four.
In a statement Boeing said: “Wedgetail is the world’s most advanced, capable and reliable command-and-control aircraft. It will provide the RAF with a combat-proven capability that is low risk and unmatched. We don’t comment on commercial matters.”
A MoD spokesman said: “We regularly discuss equipment programmes with our partners, particularly when it comes to making savings and cutting costs, where appropriate. We are not prepared to provide a running commentary on these discussions.”