A POWERFUL committee of MPs is to investigate the costs of Scottish independence to defence jobs and contracts as well as its impact on the make-up of the UK's military forces.

It will produce a report on one of the key issues in the independence debate with its findings certain to be seized upon by politicians eager to make the case for or against Scotland staying within the Union.

At present, Scotland benefits from more than £1.8 billion a year in defence contracts, with thousands of people working directly and indirectly in the shipbuilding industry. The Ministry of Defence alone employs around 20,000 people north of the Border.

Sources close to the House of Commons Defence Committee insist its inquiry will be an "informed in-depth" look, from a UK perspective, at the implications for national defence if Scotland becomes independent.

The committee is Tory-led, and has Scottish Labour members but no SNP representation, although Scottish Government ministers are expected to be called to give their views along with UK ministers, present and former armed forces chiefs, as well as experts from defence think-tanks.

The investigation is expected to take several months, with the report to be delivered by the end of the year. It will look in particular at what Scottish independence will mean for the British Army, the Royal Navy and the Royal Air Force in terms of manpower, equipment and bases.

There is also the deeply contentious issue of Faslane, home of the UK's nuclear deterrent. The SNP has made it clear nuclear weapons will be removed from an independent Scotland.

The inquiry is also expected to look at the issue of Nato membership. Research suggests the Nationalists are deeply divided over Alex Salmond's plan to pull an independent Scotland out of the international body with more than half of the SNP's grassroot members disagreeing with it.

One MP said: "How would you begin to unpick the armed forces should Scotland go independent? It's a very complex subject, but it's right we start asking the questions now so we have an idea of where we might end up."

Last night, Angus Robertson, for the SNP, told The Herald: "Scotland's defence interests will be best served by independence, which will enable us to dump the obscenely expensive Trident nuclear weapons and invest in our conventional forces. Post-independence, the SNP supports continuing co-operation with the rest of the UK, including basing, training, logistics and procurement.

"We trust any committee inquiry will also investigate the £5.6 billion defence underspend and 10,500 defence job losses in Scotland over the last decade within the Union."

Defence has already proved a thorny issue in the independence debate. Last year, Mr Salmond claimed an independent Scotland might share military facilities with England.

More recently, the First Minister said the recent UK defence review had produced a template of how the armed forces would look in an independent Scotland, explaining that one naval base, one air base and one mobile armed brigade was "exactly the configuration" required for a Scottish Defence Force.

This led to accusations of hypocrisy from Labour, which claimed the FM,

having denounced the Coalition cuts, had now embraced them, while Philip Hammond, the Defence Secretary, said of the SNP strategy: "The UK armed forces are a highly integrated and very sophisticated fighting force. The idea you can sort of break off a little bit, like a square on a chocolate bar, and that would be the bit that went north of the Border, is frankly laughable."

The committee investigation comes as Labour warned yesterday Scottish independence would result in thousands of job losses in the Clyde shipyards – a claim branded "desperate scaremongering" by the SNP.

Lord West, the former head of the Royal Navy and a security minister in Gordon Brown's Government, claimed there would be "no way" a future Government in London, post- independence, would place orders for warships in a foreign country.

Jim Murphy, the Shadow Defence Secretary, said: "It's crystal clear if we leave Britain, then we leave the Royal Navy. If we lose the Navy, we lose the work in the yards." He added: "It's time for the Nationalists to come clean."

Last night, Bruce Crawford, SNP Cabinet Secretary for Parliamentary Business and Government Strategy, hit back, saying: "It is the second-to-none Scottish skills' base and technical expertise that brings orders to the yards and that will continue after independence."

He branded Lord West's remarks a "disgraceful attack on Scottish yards".

"This desperate scaremongering from former Labour Minister Lord West is made without a stitch of evidence," declared Mr Crawford.