Information Commissioners in both Scotland and England have been urged to intervene in a bid to get the UK Government to reveal details of unpublished polling on attitudes to independence.
SNP MSP Bruce Crawford has written to both Christopher Graham in England and his counterpart in Scotland, Ken Macdonald.
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The UK Government has faced repeated calls from the SNP to make public the findings of the research, with Mr Crawford claiming £300,000 of public cash had been spent on it.
In his letters, he claimed the "true cost of the polling conducted by the UK Government on the independence referendum is in fact £299,100, substantially more than previously admitted".
He said that "while this level of Government expenditure on political polling should always be considered worthy of public scrutiny", this was "perhaps even more necessary" after press reports that the findings have been shared with the Better Together campaign to keep Scotland in the UK.
The former Scottish Government minister said he had contacted the Information Commissioners because the UK Government has failed to publish the details following Freedom Of Information (FOI) requests.
Mr Crawford said: "The UK Government has spent £300,000 of public money on what is essentially private polling for the No campaign - it is unacceptable that taxpayers are expected to bankroll the No camp in this way.
"With the true cost of this polling seemingly rising all the time - and with the UK Government refusing to publish the details in response to FOI requests - I have written to the Information Commissioners north and south of the border asking that they intervene to ensure that the FOI requests are properly responded to before the referendum.
"The UK Government has tried to fob off FOIs by saying that the polling was used to formulate Government policy. This excuse just doesn't wash when the results have been shared with the No campaign - and the policy of the UK Government was already avowedly anti-independence.
"It doesn't matter how bad the poll's findings are for David Cameron and the No campaign - people in Scotland paid for these polls and they have a right to see the results in full."
Scottish Secretary Alistair Carmichael was called on to publish the polls when he appeared before MSPs at a Holyrood committee last month.
He told members of the Scottish Parliament's Economy Committee: "You know the rules as well as I do on publication of polling information, if you publish any of it you publish all of it. 'We've published none of it, we will continue to do so. That was work that was done to inform Government policy.''
A UK Government spokesman said: "These costs have been openly and transparently put into the public domain via the Cabinet Office website. It's normal practice for governments to carry out this sort of polling, especially around an issue as important as the referendum.
"We are carrying out this research to understand how best to identify and communicate with our audiences. The recent public polls are clear indicators of what Scotland thinks about leaving the UK."
Meanwhile, the SNP's Westminster leader has rejected claims that he put pressure on the whisky industry not to enter the debate on Scottish independence.
The makers of a documentary to be aired tonight contacted 50 companies and business leaders believed to have concerns about independence.
Five told the programme privately that they had been contacted by the Scottish Government and said they ''felt pressured to stay quiet about their views''.
Gavin Hewitt, the former chief executive of the Scotch Whisky Association, said that he or senior members of his staff have met with Angus Robertson, the SNP leader at Westminster, on at least six occasions over the past two years.
''He and the SNP have regularly tried to get the message to the Scotch Whisky Association (SWA) that the Scotch whisky industry should stay out of the independence debate,'' Mr Hewitt told The Great British Break Up, by Channel 4's Dispatches.
''He was, I think, trying to neuter business comment. There was a genuine fear that in fact if we were seen to scupper by coming out publicly against independence, there would be retribution down the track.''
In response, the Scottish Government told the programme that Mr Hewitt's claims about Mr Robertson are ''utterly false''.
Mr Robertson said today: "I totally refute the allegations, especially given that both Gavin Hewitt and his successor Peter Frost have both said to me that they don't take a position on constitutional issues. Mr Hewitt publicly endorsed the case for a No vote last month, which of course he is perfectly entitled to do.
"As the MP representing more than half of Scotland's malt whisky distilleries, I work hard to promote the industry and its heartland producing region Speyside, as well as liaising with the SWA on industry regulation and taxation.
"I met Gavin Hewitt and other SWA colleagues regularly at meetings of the Westminster parliamentary whisky industry group, SWA receptions at the annual SNP conference and Dover House, and the Spirit of Speyside Whisky Festival. I have never had a private unaccompanied meeting with Gavin Hewitt. These meetings all happened in the company of colleagues.
"It is also the case that Mr Hewitt stressed to the Herald newspaper's UK political editor last month that his claims of intimidation had not been in the context of the independence referendum - which is the opposite of what is being reported now. That is not a matter for me.
"What is a matter for me, and what I am very clear about, is that there is nothing in my conduct which answers to Mr Hewitt's description."
The programme also spoke to Professor Patrick Dunleavy, public policy chair at the London School of Economics, who has previously stated that the UK Government misrepresented his research when it published its analysis of the fiscal implications of independence.
The Treasury used Prof Dunleavy's figures to estimate that it could cost between £1.5 and £2.7 billion to set up an independent Scotland, but the economist later said the initial set-up costs to duplicate core Westminster functions would be around £200 million.
Speaking to Dispatches, he said: ''It's very hard to describe it in polite terms actually, it's very crude, it's alarmist, it's not been checked and it rests on a whole series of, you know, false steps... that makes this a very dubious document. A dodgy dossier, you might call it.''
A UK Government spokesman told the programme it had ''cited several external sources'' to provide context in its calculations for the set up costs.
Mr Robertson added: "It is high time the UK Government retracted their bogus claims on the establishment of an independent Scotland, and apologised for their 'dodgy dossier'."