Alex Salmond has won a key television debate against the leader of the campaign to keep Scotland in the United Kingdom, a snap poll has found.

Research by ICM for the Guardian newspaper showed 71% of people questioned thought the Scottish First Minister had been the better performer in the BBC clash, compared to 29% for Better Together leader Alistair Darling.

A similar survey after the first head-to-head debate between the two men last month suggested the former chancellor had scored a narrow victory over the SNP leader.

In both televised debates, the issue of which currency an independent Scotland would use was at the heart of the arguments.

Mr Darling again repeatedly pressed the First Minister to set out his plan B for a currency if a formal deal could not be agreed with the rest of the UK to allow an independent Scotland to retain the pound.

But the former chancellor tonight appeared to accept that Scotland could use the pound regardless of whether Westminster signed up to such an arrangement.

He said: "Of course we can use the pound...we could use the ruble, we could use the dollar, we could use the yen. We could use anything we want."

Mr Salmond said: "The key point we have heard tonight is that Alistair admitted a few seconds ago we could use the pound anyway. We didn't need permission.

"Totally different from what the Chancellor of the Exchequer said a few months ago, when he said, if you walk out of the UK, you walk out of the pound.

"Remember that, we have heard it tonight. They cannot stop us using the pound, the most important revelation of this debate."

Blair Jenkins, chief executive of the pro-independence Yes Scotland campaign, said afterwards: 'This was an overwhelming victory for Yes. The First Minister's message was clear, optimistic and passionate and spelled out a no-nonsense message of the positives and opportunities of independence."

But Better Together campaign director Blair McDougall said: "Alex Salmond still can't give a credible answer on currency. While the world was watching he even went as far as to threaten to default on our debts."

On currency Mr Salmond insisted he was seeking a mandate from the Scots to call for a formal currency union with the rest of the UK - an option which has already been ruled out by the Conservatives, Labour and the Liberal Democrats.

Despite that, the First Minister said: "I want people to back the proposition that we should share sterling in a currency union.

"That mandate is crucial, and that is what I want people to support, because I believe if they support it and send me into negotiations as First Minister then that will be the outcome."

But he also said he had "set out the options to point out there are other things we could do", highlighting a flexible currency union such as Sweden and Norway's and the fixed exchange rate that Denmark and Hong Kong share.

Mr Salmond then added: "We cannot be stopped from using the pound anyway."

He told Mr Darling: "I set out the options very clearly - three Plan Bs for the price of one. They are just like buses ... you expect one and then three turn up at once."

He stressed if there is a Yes vote on 18 September he would "argue what is best for the people of Scotland", which could be a currency union.

"If I was to go in arguing for second best, then second best is what we would get," he said.

Mr Darling, however, told the SNP leader: "You are taking a huge risk if you think it is just all going to fall into place."

The Labour MP insisted: "I think the currency union would be bad for Scotland because our budget would have to be approved not by us, but what would then be a foreign country. It wouldn't be best for the rest of the country either."

The debate, staged at Glasgow's Kelvingrove Art Gallery and Museum, saw heated exchanges between the rival politicians, who had to be told not to talk over one another.

On the future of the NHS the Better Together leader accused the pro-independence campaign of scaremongering with claims that a Yes vote is needed to protect the health service north of the border from privatisation.

Mr Darling said: "What we need is less of that scaremongering and a realisation we all want the NHS to do well, we all want it to be there at the point of need, but to do that you need funding.

"Frankly taking on risks, not even knowing what currency you've got is the real threat to the National Health Service."

But Mr Salmond insisted spending cuts south of the border could hurt the health service in Scotland if the referendum resulted in a No vote

He said: "That is why to have a health service we can all trust and rely on we've got to have a health service where we have financial control as well as policy control, so we can keep the National Health Service as the greatest public institution in Scotland."

The SNP leader went on to tell Mr Darling he was "in bed with the Tory Party" over welfare reforms  - with this denied by the Better Together leader, who argued it made sense to spread the cost of providing social security across all of the UK.

Mr Darling said: "We know there are people with disabilities, we know we've got an ageing population that will require more medical care, we know we've got a falling working age population. Why take that burden on five million people when it could be pooled and shared across 63 million, it makes no sense whatsoever."

Closing the debate he insisted that uncertainty over currency could "bring a country to its knees".

The former chancellor said: "I know there are some who are thinking about giving independence a chance, but when we can't be told about currency, I don't think that can be trusted."

Mr Salmond said an independent Scotland would face challenges, and would "have to rise to these challenges to solve them".

But he argued the rival No campaign "has absolutely nothing positive to say about the future of this country".

Earlier today Professor Joseph Stiglitz, a leading US economist from the Scottish government's council of economic advisers, hit out at "fear tactics" used by the campaign against Scottish independence.

Prof Stiglitz, a member of the Fiscal Commission Working Group, insists the row over what currency a separate Scotland would use is "a lot of to do about nothing".

He believes a currency union between an independent Scotland and the rest of the UK could work.

He dismissed the refusal of the main British political parties to agree to such a deal as "bluffs".

However, Prof Stiglitz also stressed that there is a range of options for the currency of an independent Scotland.

He pointed out that Panama has used the US dollar for more than a century, while countries such as Canada and some European nations have adopted their own currencies successfully.