ALEX Salmond has mounted a robust defence of his under-fire currency proposals for an independent Scotland as he expressed satisfaction at the outcome of his historic TV referendum debate with Alistair Darling.

The First Minister pointed to polling evidence that showed he came out on top among undecided voters in Tuesday night's prime-time clash with the leader of the pro-UK Better Together campaign.

Speaking at a conference organised by pro-independence group Business for Scotland, the SNP leader also defended his claim that an independent Scotland would secure a currency-sharing deal with the rest of the UK, despite the Treasury publicly ruling that out.

During uncomfortable exchanges for the First Minister in the debate, the former Labour Chancellor described the plan as "stupidity on stilts" and challenged Mr Salmond repeatedly to set out his "Plan B".

At the meeting in Edinburgh y­esterday, a defiant Mr Salmond insisted he was right to duck the question despite jeers from members of the audience at the Royal Conservatoire in Glasgow.

He repeated his threat that the ­country could continue to use the pound unilaterally after a Yes vote and refuse to take on a share of the UK's national debt. However, Mr Salmond claimed this was not his Plan B.

He said: "That would be quite attractive. But obviously it also tells you why it ain't going to happen.

"There is no way that a UK ­Chancellor is going to allow himself to be in a position where Scotland gets off scot-free in terms of the debt."

He said he would not entertain an alternative plan because he was seeking a "sovereign mandate" to negotiate a currency union in the event of a Yes vote.

Labour peer Lord McFall of Alcluith, who as an MP chaired the Commons Treasury Select Committee, said Mr Salmond had lost the argument on TV, but now "appears to have lost the plot" with his latest comments.

Lord McFall added: "Refusing to pay our debts would leave a separate Scotland with a bad credit rating and push up everyday costs for families here from day one. Alex Salmond is a man without a plan on currency."

On Tuesday night, a snap ICM/Guardian poll of 512 Scottish viewers showed 56 per cent thought Mr Darling had come out on top in the debate, compared to 44 per cent who felt Mr Salmond had won, once those unable to pick a winner were discounted.

But Mr Salmond took heart from other figures in the survey that showed three-quarters of people who were unsure how to vote in the r­eferendum after the debate believed he had won the contest.

"I'll take the results of the ICM poll," said Mr Salmond. The poll also showed a slight overall rise in backing for a Yes vote, with a significant rise in support among women.

Yes Scotland, the main pro-independence campaign, said the figures indicated it was "winning where it counts," but polling expert Professor John Curtice said neither side had secured a decisive advantage after the showdown, which was watched by 1.7 million people.

Commenting on the debate on a visit to a factory in Fife, Mr Darling said: "Scotland needs the answers to the basic questions from Alex Salmond. We need to know what currency a separate Scotland would use, we need to know what Plan B is."

Scottish Labour will today deliver a giant pound coin to the First Minister's official residence, Bute House in Edinburgh.

Mr Salmond, meanwhile, rallied SNP MSPs at a parliamentary group meeting at Holyrood.

Today Yes Scotland will launch a poster campaign on the theme of the "opportunity" of independence.