ALEX Salmond has defended his plan to slash corporation tax in an independent Scotland after it emerged one of his key economic advisers cast doubt on its ability to boost the economy.

The First Minister has put a reduction in the main tax on business profits at the heart of his economic programme for a go-it-alone Scotland.

But it emerged yesterday that Professor Joseph Stiglitz, one of the eminent economists who helped draw up the plans, denied it would lead to greater investment.

In Montreal last month, the Nobel Prize-winning academic said: "Some of you have been told that lowering tax rates on corporations will lead to more investment.

"That fact is not true. It is just a gift to the corporations, increasing inequality in our society."

The comments emerged days after a business-focused think tank, the Scottish Council for Development and Industry, said its members did not want to see a race between an independent Scotland and the UK towards lower taxes.

Mr Salmond's plan to cut corporation tax to 3p below the UK rate has also been criticised by Yes vote allies in the Scottish Greens and Scottish Socialist Party.

Pro-UK politicians claimed the move would probably not be allowed if an independent Scotland and the UK agreed a currency union to share the pound.

However, Mr Salmond insisted it would bring investment and jobs.

At First Minister's Questions, he said: "We have analysed it and it said it would create 27,000 jobs and an increase in GDP of over 1% over the medium term.

"Our policy of setting a competitive rate of corporation tax and then collecting it is superior to the Labour/Tory policy of setting a rate of corporation tax and then forgetting to collect it from key companies."

However, Scots Labour leader Johann Lamont said: "I agree with the Nobel prize-winning Joseph Stiglitz and the businesses, the unions, the professionals who all say the First Minister is wrong."

Mr Stiglitz's comments came in a speech to the national convention of Canada's New Democratic Party in Montreal.

Last year, giving evidence to a committee of MSPs by video link, the expert spoke in guarded terms about the SNP's proposal to retain the pound in a currency union with the UK, saying that "in the long run, Scotland will have to re-examine its institutions".

Mr Salmond's figures were based on a 2011 Scottish Government analysis which predicted the impact of cutting corporation tax from 23% to 20%.

Since then the UK Government has signalled a cut to 20% from 2015, suggesting the SNP would cut the rate to 17%.

The row came as the two sides in the referendum battle continued to clash over the start-up costs of an independent state. Yes Scotland defended a campaign video insisting "initial start-up" would be met by £300 million savings from the likes of Trident nuclear weapons.

A spokesman said: "Scotland already has and pays for much of the key infrastructure of an independent country, and any initial start-up costs will be more than offset by the very significant savings from no longer paying for the Westminster system."

The Scottish Government declined to put a figure on the overall start-up costs. Asked for an estimate of the cost, the First Minister's chief spin doctor said: "The key point to stress is that an independent Scotland would inherit a fair share of UK assets."

Better Together, the cross-party pro-UK campaign, produced a list of spending areas, including health and schools, which the SNP previously said should be supported by savings from scrapping Trident.