THE SNP’s blueprint for independence is based on “misleading analysis” and would have seen spending on public services slashed by around £60 billion if it had applied over the last decade, a new study has claimed.

These Islands, a pro-UK think tank, insisted the party’s Growth Commission actually strengthened the economic case for Scotland remaining in the union.

Its findings have drawn support from a range of leading economists including Glasgow University professors Ronald MacDonald and Jim Gallagher, Strathclyde’s Professor Brian Ashcroft and Brian Quinn, the former acting deputy governor of the Bank of England.

Opposition politicians insisted the report was “damning”, but the SNP said unionists were "clearly rattled" by the boost the blueprint had given to the independence cause.

The SNP’s Growth Commission report, which was led by former MSP Andrew Wilson and published earlier this year, claimed living standards in Scotland could "equal the best small countries in the world" within a generation of independence.

Its key recommendations included cutting the country's deficit and keeping the pound for at least a decade.

But These Islands insisted the Commission had “singularly failed to make a coherent economic case for independence; in fact their work helps highlight the economic benefits of Scotland remaining part of the UK.”

It accused the report of tacitly accepting the current austerity policies of the UK Government which it claims to reject.

And it argued that if the Commission’s model for deficit reduction had been applied over the last decade, Scotland would have spent around £60 billion less. In 2016/17, public spending would have been £8bn lower.

It said the Commission itself had accepted that keeping the pound "for a possibly extended transition period" would be damaging to Scotland’s financial services sector, while its report avoided discussing how or when an independent Scotland might qualify for EU membership.

Kevin Hague, chairman of These Islands and the author of the new paper, said it showed “the SNP's Growth Commission report is objectively more optimistic than the 2014 White Paper, not more realistic as has been widely claimed”.

He added: "In fact the Growth Commission's report contains highly misleading analysis, fails to address the key economic questions and – we presume unintentionally – actually strengthens the economic case for Scotland remaining in the UK."

His report claims the Commission’s recommendations would be likely to lead to austerity far greater than anything Scotland has recently experienced, or is forecast to experience within the UK.

Scottish Conservative shadow finance secretary Murdo Fraser said the analysis showed the SNP “is now making even wilder claims about secession than Alex Salmond did prior to the referendum”.

He added: “Quite simply, they are making it up as they go along.

“As everyone apart from the SNP acknowledges, independence would mean cuts on a scale never seen in Scotland – damaging every hospital, school and public service in the country."

Shadow Scottish Secretary Lesley Laird said it was now “abundantly clear that the SNP’s plans for an independent Scotland would result in austerity cuts that not even [former Tory Chancellor] George Osborne would have dared to implement”.

She added: “If these proposals were put into practice Scotland’s already under pressure public services would be devastated, with spending slashed on the NHS, schools, and on other vital areas.”

But an SNP spokeswoman said: “If the Growth Commission’s approach had been followed over the last decade, the £2.6bn of cuts to the Scottish Government’s budget by Westminster would have been completely reversed, with the prospect of additional public spending beyond that.

“The commission has kick-started a serious and welcome debate over Scotland's future, and unionists are clearly rattled by the boost it has given to the independence case, with last month’s Scottish Social Attitudes survey showing that the numbers who view independence as positive for Scotland’s economy now outnumber those who believe otherwise."