Think tank: Thousands of soldiers face sack no matter who wins General Election

A new report by the Royal United Services Institute (Rusi) warns of a multi-billion pound black hole in the Ministry of Defence's finances that could see up to 30,000 staff axed.

The warning came as Labour accuses the Conservatives of planning "unprecedented, risky and extreme" cuts to public services, more than double what have publicly admitted.

Thousands of soldiers have already lost their jobs over the last five years under the Tory-Lib Dem Coalition's austerity measures.

David Cameron has pledged not to cut Army numbers further while he is Prime Minister. But former defence minister Nick Harvey warned that MoD officials were already drawing up plans to cut tens of thousands of personnel in a debate in the House of Commons earlier this year.

The Rusi report, written by research director Professor Malcolm Chalmers, is published as Mr Cameron faces intense pressure from Tory backbenchers to sign up to the Nato target of spending two per cent of GDP on defence.

The think tank said that its analysis of the Tory, Labour and Liberal Democrat parties' spending plans suggested MoD could be facing a real-terms budget cut of up to 10 per cent over the next four years.

The report warns that the Army is likely to be hardest hit - losing potentially 20,000 of the estimated 30,000 military personnel axed.

But the Army could have to bear even more of the brunt because of the need to crew the new aircraft carriers being built on the Clyde.

The report also warns that any savings from the multi-billion pound project to replace Trident would be difficult, unless the scheme is scrapped altogether. Shadow justice secretary Sadiq Khan said yesterday a Labour government would commit to renewing Trident.

Meanwhile, the Rusi paper suggests Mr Cameron's pledge to increase the defence equipment budget could mean even more jobs lost - around 42,000 in total, cutting the Army to just 50,000 service men and women, under the most pessimistic scenario.

Under even the most optimistic scenario around 15,000 jobs would have to be shed across the three services.

Even if defence was ring-fenced, a pledge no party has yet made, it says around 15,000 personnel would still have to be shed by 2020.

The Rusi paper estimates that to reach the two per cent level defence spending would have to rise by £3 billion next year and almost £6 billion by 2019-20.

The paper says: "In the context of wider austerity in public spending, such an increase is not plausible.

"The Government is not yet convinced that strategic security risks are high enough to justify an exemption for defence from austerity."

Today shadow chancellor Ed Balls will warn that the full extent of Tory plans to cut spending to 1930s levels, as set out in last year's Autumn Statement will lead to the biggest cuts in any period since the end of World War Two.

Mr Balls will say: "It's no wonder that the Institute for Fiscal Studies has said these cuts are 'colossal' and questioned whether they could be delivered without 'a fundamental reimagining of the role of the state'."

A UK Government spokesman n the Rusi report said: "Decisions on spending after the financial year 2015/16 will be determined in the next spending review.

"Over the next decade we are committed to spending £163bn on equipment and equipment support to keep Britain safe. That includes new strike fighters; more surveillance aircraft; hunter killer submarines; two aircraft carriers; and the most advanced armoured vehicles.

"The Prime Minister has said that he does not want to see our regular armed services reduced below the level that they are now and remains committed to growing the Reserves to 35,000."

An SNP spokesman said: "The UK Government's obsession with Trident nuclear weapons is already causing an unsustainable drain on armed services and halting the waste of £100bn on Trident's replacement is something a strong team SNP MPs will make an absolute priority."

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