Research suggesting that more than half of voters in England are opposed to an independent Scotland using the pound has been condemned as "flawed" by an expert adviser to Alex Salmond.
A total of 53% of those questioned for the Future of England Survey disagreed with the idea of Scotland continuing to use the pound if it left the UK.
Just under a quarter (23%) were in agreement that an independent Scotland should still use sterling while 15% said they neither agreed or disagreed and 9% did not know.
More than 3,600 people in England were questioned by YouGov for the research, which was undertaken by Cardiff University and the ESRC Scottish Centre on Constitutional Change at Edinburgh University.
It comes as the key issue of what currency an independent Scotland would use comes under scrutiny in the run-up to the independence referendum on September 18.
But Crawford Beveridge, chair of the Scottish Government's Fiscal Commission Working Group which considered the issue, concluded: "The premise to the question is, however, flawed."
The Fiscal Commission, which includes expert economists, concluded if there was a Yes vote a currency union would be the best option for both Scotland and the rest of the UK.
Mr Beveridge added that the decision on what currency Scotland should use if it became independent could not be determined south of the border.
"A currency is not something which can only ever be used by a single country and one country cannot prevent another from using it," he said.
"Indeed the choice of currency is determined by the laws of a country itself and, more importantly, the confidence people have in it.
"People can choose to trade in whichever currency they wish. What is up for debate and negotiation is the form of governance for the currency.
"And, in this regard, I remain firmly of the view that a well-designed monetary union is the best option for both Scotland and the UK post-independence."
While the three main parties at Westminster have all ruled out entering into a currency union with an independent Scotland, Mr Beveridge added: "I'm certain that should the people of Scotland vote for independence the highly-charged political atmosphere will subside and common sense will lead to negotiations on a formal monetary union."
Labour MSP Jackie Baillie said: "A currency union would not happen if we left the UK.
"That's why we need to know Alex Salmond's plan B for what would replace the pound. Would we rush to adopt the euro? Or would we set up a separate unproven currency?
"With just one week until up to one million postal votes are sent out across Scotland, it beggars belief that people are being asked to make such a huge decision without knowing what currency we would use.
"This really matters to people. How can we talk about paying for our schools and hospitals in a separate Scotland if we don't know what currency we would use for that? How can families plan for the future if we don't know what money our wages, pensions and benefits would be paid in?"
She stated: "It is not surprising that the majority of people in England do not support a currency union.
"It wouldn't work for Scotland or the rest of the UK. For us in Scotland it would mean handing over control of our economy to what would then be a foreign country."
Deputy First Minister Nicola Sturgeon cited a separate Panelbase survey which showed 71% of people in Scotland agreed that the "pound belongs to Scotland as much as it belongs to the rest of the UK", with 19% disagreeing with this.
Ms Sturgeon said that research, which was commissioned by Yes Scotland, "shows that the No campaign is increasingly out of touch with Scottish opinion on the pound".
She added: "The people of Scotland overwhelmingly believe, by a margin of nearly four to one, that the pound would belong to an independent Scotland every bit as much as the rest of the UK. And they are right, because the pound is Scotland's currency too."