Shipyards on the Clyde and at Rosyth may be hit as major equipment projects for the armed forces face being delayed so that the Ministry of Defence can stay within budget.

Giving evidence to the Commons Defence Committee, General Sir Kevin O'Donoghue, the Chief of Defence Materiel, said that the MoD was having to "tailor" its programmes to the cash available.

The MoD is currently reviewing all its major equipment programmes - including the Royal Navy's two planned new aircraft carriers, the Army's new family of armoured vehicles known as Fres (Future Rapid Effects System), and the replacement for the Lynx helicopter.

The aircraft carriers are due to be constructed at the Govan and Scotstoun shipyards and Rosyth, with other work carried out at Portsmouth.

Committee chairman James Arbuthnot said that there was a belief among defence manufacturers that projects would be "stretched out" - spreading the costs over a longer period - rather than axed altogether.

Gen O'Donoghue replied: "That is certainly one of the options."

He rejected an estimate by the Royal United Services Institute (Rusi) think tank that there was a £15 billion shortfall in the equipment budget.

"I suggest these figures that you might have picked up from Rusi and other places are a tad uninformed," he said.

However he acknowledged that funding was an issue in determining how individual programmes would proceed.

"I don't think you can simply say that the equipment budget is underfunded. It is a question of balancing aspirations and requirements and the amount of money available," he said.

"We have to tailor the money available to what is really required."