Thousands of civil servants are to lose their jobs at the Ministry of Defence, in addition to some 25,000 posts that were already set to be cut.
The Guardian has seen a letter, being sent out by the department's top civil servant, which says a further 7,000 civilian jobs are to be cut in a bid to bring its budget under control.
The letter says the MoD needs to "bear down further on non-front line costs".
Union leaders and defence officials have expressed concern at the decision.
The cuts were not mentioned in Defence Secretary Liam Fox's last statement to Parliament, which revealed significant extra cuts to Army numbers.
The MOD is already trying to cut some 25,000 civilian posts over the next few years, as announced last October in the defence review.
Questions remainThat review outlined the future shape and size of Britain's armed forces, with defence spending set to fall by eight per cent over four years.
The decision taken to close more jobs will bring numbers at the MoD down by around a third over a period of nine years - to about 53,000 civilian posts by 2020.
The letter outlining the further job losses is signed by the permanent secretary, Ursula Brennan, and is being sent to all civilian staff.
It argues that the cuts are necessary and concedes that the move will raise questions which cannot "be answered immediately".
It expresses a hope that many of the job losses will be achieved by "natural wastage", with "compulsory redundancy" only being used as a last resort.
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