Princes Street, Edinburgh: The debate over Scotltish independence has become increasingly heated.

Princes Street, Edinburgh: The debate over Scotltish independence has become increasingly heated. Photo: Bloomberg

London: Support for Scottish independence has risen after Britain's three main political parties warned the Scots they would not be able to keep the pound if they left the United Kingdom, the first opinion poll following those comments showed.

The message sparked an angry response from Scottish leader Alex Salmond who said Scotland had every right to continue to use the pound and that "bullying" from London would create a backlash.

A Survation poll in the Scottish Daily Mail on Thursday seemed to bear that prediction out. It showed the gap between those who would vote for or against independence in a referendum scheduled for September 18 had narrowed to 9 percentage points. A Survation poll published on February 1 had shown a 20 percentage point lead for opponents of independence.

But Survation said the results of its latest poll were not comparable with its earlier poll as it had changed its methodology to bring it into line with other major pollsters. It said the results could be meaningfully compared to a PanelBase/Sunday Times poll which uses a similar methodology.

The Survation poll of 1005 people found 37.7 per cent support for independence, up from up from 36.9 per cent in a PanelBase/Sunday Times poll carried out  between January 29 to February 6.

It showed 46.6 per cent would vote 'no' to independence, a decline from 48.5 per cent in the earlier poll.

"It is clear that there has been a severe backlash to [British Finance Minister] George Osborne's bluster and threats on the pound," Scottish National Party deputy Nicola Sturgeon said in a statement. "... Far more people [are] more likely to vote Yes [to independence] on the back of the Westminster establishment's attempted bullying rather than No."

The debate over whether Scotland, which has a population of just over 5 million should leave the UK has become increasingly heated as the referendum vote nears.

European Commission President Jose Manuel Barroso also ruffled Scottish feathers on Sunday, saying it would be "difficult if not impossible" for any breakaway state to join the European Union.

Conducted on February 17 and 18, the Survation poll found 52 per cent of respondents thought it would be in the interests of the rest of the UK to join a currency union with an independent Scotland while only 25 per cent disagreed. The rest did not know.

Mr Salmond said blocking Scotland's access to the pound would hurt both sides of the border as currency translation costs would impact trade between Scotland and the rest of the UK.  He has argued that the pound is a shared asset and Scotland could refuse to take a share of liabilities such as the UK's £1.2 trillion debt if it was refused access.

But  Mr Osborne said Scotland would lose the pound if it voted for independence.

The Survation poll also found 65 per cent of respondents wanted Mr Salmond to come up with  an alternative plan for the currency.

So far, the pro-independence camp has trailed in polls, but the gap has narrowed this year.

A second poll from TNS also released on Thursday found 29 per cent of Scots plan to vote for independence with 42 per cent intending to vote against. It found 29 per cent were still undecided.

This was unchanged from a similar poll in early February but the poll of 996 adults was conducted before the row over the pound.

Tom Costley, head of TNS in Scotland, said the debate had stepped up a gear following the comments on the pound and by Mr Barroso.

"It may be that the recent activity, especially the firm statement by the anti-independence parties on the future of the pound, will stimulate more debate, bring out more information and help undecided voters to make up their minds."

Reuters