A Whitehall spending watchdog today delivered its latest damning verdict on the Ministry of Defence's “unaffordable” plans for buying vital equipment.

MPs blast its “lamentable failure to get a grip on the equipment plan”, saying warnings about its “serious affordability issues” have been issued “year after year”.

The Government hopes to spend billions of pounds on warships, RAF jets and armoured fighting vehicles – despite repeated criticism that it cannot afford them.

Commons Public Accounts Committee chairwoman Meg Hillier said: “The MoD knows what it’s getting wrong, we know what it’s getting wrong.

Public Accounts Committee chairwoman Meg Hillier delivered another scathing judgement on the MoD's budgeting

“For years we have made concrete proposals to improve delivery of key strategic priorities and here we are again, with the same gaps in our national defence and the same risk to our Armed Forces personnel, year after year.

“We are saying to the MoD and to the Treasury now: come back to us by the end of the year with a concrete plan for how you are going to turn this around, how you are going to do this differently, from now on.

“The nation and the Armed Forces that protect us are owed that much.”

Exasperated MPs cite repeated warnings over the MoD's 10-year equipment plan which “continues to be unaffordable despite this committee and the NAO (National Audit Office) consistently highlighting serious affordability issues in the plan year after year”.

The MoD plans to buy 138 Lightning jets for the RAF and Royal Navy

The committee's 22-page report published today says: “The 2019-2029 plan is too expensive by between an estimated £2.9billion and £13bn.

“The department has still not made the hard choices necessary to balance the plan and address the affordability gap, which arises in part from a failure to fully fund ambitions set out in the 2015 Strategic Defence and Security Review.

“The department is instead stuck in a cycle of managing its annual budget, using additional funds to offset financial pressures, and making short-term decisions which result in poor, long-term value for money.

“Plans for efficiency savings remain totally unrealistic; for example £4.7bn of savings are assumed without plans for how they will be delivered.”

Defence Secretary Ben Wallace has faced repeated questions over the affordability of some projects
An F-35 Lightning jet takes off from the Royal Navy aircraft carrier HMS Queen Elizabeth

Its study outlines grand MoD ambitions like purchasing scores of F-35 Lightning joint strike fighter warplanes, saying: “It is still committed to buying 138 F-35 Lightning jets but has made provision for just 48 in the plan.”

A major “Integrated Review of Security, Defence, Development and Foreign Policy” is underway in Whitehall.

An MoD spokeswoman said: “We want our Armed Forces to have the very best ships, aircraft and vehicles, that’s why we have delivered the equipment plan within budget for the third year running.

“As the PAC acknowledges, managing complex defence programmes can be challenging and we continue to reduce the gap between our budget and predicted costs, achieving £7.5bn of efficiency savings last year and securing an extra £2.2bn for defence.”