Image caption The latest cuts will bring numbers at the MoD down to about 53,000 civilian posts by 2020

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, sent by the department's top civil servant, which says a further 7,000 civilian jobs are to be axed.

Union leaders have called the decision "shameful" and defence officials have also expressed concerns.

The MoD said the cuts would ensure the front line had maximum funding.

The letter says the MoD needs to "bear down further on non-front line costs".

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 remain

That 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".

Analysis This comes from a letter from the permanent secretary and it follows the emergence of a budget shortfall. A few months ago it emerged there was an overspend of £1bn just for the last year but they are now saying that from 2015, the overspend could be £10bn. The unions argue it's political. They say there is no need to get rid of so many people in civilian jobs. They say it's ideological shrinkage of the public sector in the defence department. But the permanent secretary says she will explain why the cuts are necessary (later) and they are in order to bring non-front line costs down. The overspend comes from an internal review at the the MoD of their financial liabilities over the next decade. It says the risk of cost-overruns on equipment has been understated in the SDSR (strategic defence review).

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.

The Public and Commercial Services union (PCS) said it was "totally unreasonable" for the MoD to be cutting so many posts when efforts were still being made to reduce the previously announced cull of jobs.

The union's general secretary Mark Serwotka said cutting so many civilian and military jobs could put lives at risk.

"This is a shameful way to treat anybody, far less the people who serve on the front line, and those who support them.

"Since the defence review announcement in October, PCS has been thwarted at every turn in our attempts to find out where these cuts will be made and what impact it will have on the front line.

"How can the MoD announce more job cuts when they have no idea how they will run the department just now?"

Mr Serwotka said the union had been working on a programme for defence that identified and reduced waste and freed up service personal to serve in the front line by "civilianising" military posts it sees as non-essential.

He added that according to the MoD's own records, it spends approximately £6bn per annum on external expenditure such as consultants.

An MoD spokesman said: "The government has tackled the £38bn black hole in the MoD's finances, delivering substantial savings through difficult but necessary decisions.

"The aim of these cost savings is to ensure that the maximum funding is available for the front line.

"We hope to achieve these efficiencies through natural wastage wherever possible with compulsory redundancy programmes serving only as a last resort."