DANNY Alexander will today seek to debunk the claims of the Scottish Government's White Paper, branding the assertion by Alex Salmond and his colleagues that an independent Scotland would be entitled to one third of the UK's £1.3trillion assets as "fantastical".

In a speech in Edinburgh, which will coincide with the publication by HM Revenue and Customs of new oil and gas revenue figures, the Treasury Minister will claim the Nationalists' assertions on North Sea income are at best ill-informed and at worst deeply misleading.

"The fact is that their £1.5tr figure for the value of oil left in the North Sea doesn't include any costs for getting the oil out of the ground and into the petrol pump."

The Highland LibDem MP will point out how between 2012 and 2017, the SNP Government's most cautious North Sea revenue forecast was £41bn compared to the £25bn predicted by the Office for Budget Responsibility, the UK Government's forecaster.

"It doesn't matter how deep you drill into the figures, they simply don't add up," Mr Alexander will declare," calling on the Scottish Government to publish "realistic forecasts".

He will stress: "The Scottish Government must confront the fact that it is promising tax revenues and public spending that it cannot deliver. It should revise its oil and gas forecasts... It is the very least that the Scottish voters deserve."

He will accuse the First Minister and his colleagues of "ignoring the reality" that it was the UK Government which stepped in to save Royal Bank of Scotland.

But Mr Swinney said that to have a "shred of credibility" any Westminster analysis would not only set out Scotland's share of the UK's liabilities but also its share of the UK's assets, which would run into billions of pounds.

"Scotland's share of UK assets will be realised in a combination of ways; through physical assets, cash transfer and continued use of assets through shared service agreements," explained the Scottish Finance Secretary.

"Assets located elsewhere in the UK will be included in negotiations as Scotland has contributed to their value over a long period of time. For physical assets like these, the equitable outcome may be to provide Scotland with an appropriate cash share of their value."