THE overall cost of setting up an independent Scotland has not been calculated, the Scottish Government's chief economic adviser has confirmed.

Dr Gary Gillespie told Holyrood's economy committee that detailed work on the cost of setting up new institutions to replace the Ministry of Defence, Department for Work and Pensions, Foreign Office and other UK bodies had not been carried out.

The Scottish Government has faced claims - strenuously denied - that it was concealing calculations from the public. Asked yesterday by committee convener Murdo Fraser whether detailed work on costings had been carried out but kept out of the White Paper, Dr Gillespie replied: "No."

Finance Secretary John Swinney said it was impossible to put a "precise number" on the set-up costs because arrangements to provide pensions and collect taxes would be the subject of negotiations with the rest of the UK in the event of a Yes vote.

The Treasury has claimed the figure could be as high as £2.7 billion - a cost dismissed as wildly exaggerated by the academic upon whose work the calculation was based.

Mr Swinney said the gaffe highlighted the difficulty of producing a meaningful figure. But Tory MSP Mr Fraser said: "This was an astonishing admission from the chief economic adviser that no sums have been done for the start-up of a separate Scotland."

The row came as Chief Secretary to the Treasury Danny Alexander dismissed Scottish Government forecasts for economic growth, if the country becomes independent, as "pie in the sky" and drawn up on the "back of a fag packet".

Also giving evidence to the committee he said the Scottish Government had made "massively optimistic" projections about tax revenues from North Sea oil.