AN independent Scotland would have two choices on currency, one of which - using the pound informally and refusing to share any of the burden of the UK national debt - would be a "pretty attractive option", an adviser to Alex Salmond has said.

The comments, made by SNP MSP Joan McAlpine at a public meeting, appear to fly in the face of the Scottish Government's official position that it has a single "Plan A" on the issue of currency - a formal union with the rest of the UK.

Ms McAlpine's remarks suggest the SNP may also be considering the Plan B of an informal currency union, known as sterlingisation.

Under an informal currency union, Scotland could use the pound but without the Bank of England as lender of last resort for Scottish banks.

Chancellor George Osborne, Labour and the Liberal Democrats have all ruled out a formal currency union, but the First Minister says this is a bluff.

He argues that if an independent Scotland was not allowed to share the pound, it could refuse to take its £100 billion per capita share of UK debt.

Ms McAlpine, the First Minister's parliamentary liaison officer, was asked about a currency "Plan B" at a Yes campaign meeting in Lockerbie, a video of which can now be viewed online.

She said: "They cannot stop us using the pound.

"If we did do that without formal currency union we wouldn't inherit any of the debt, which I think is a pretty attractive option.

"So, perhaps, watch this space. You know, if there was a possibility of us saying, 'Right that's fine, you keep all the assets and you can keep the debt as well'."

Ms McAlpine said even "unionist economists" had acknowledged the attractiveness of an independent Scotland starting with no debt.

"So I think that's probably the two choices that you're looking at," she concluded.

A Better Together spokesman said: "It beggars belief that one of Alex Salmond's closest aides would make these comments without his approval.

"It's clear the SNP are preparing to ignore the advice of their own Fiscal Commission, which specifically ruled out this reckless proposal. Walking away from our debt would add to the cost of living for hard working Scottish families, adding thousands to the cost of mortgages, credit card bills and car loans."

The Scottish Government refused to comment.

An SNP spokeswoman said: "The Fiscal Commission report indicated an independent Scotland has a range of currency options but that a currency union between Scotland and the rest of the UK is the best option not just for Scotland but also for the rest of the UK, and that is what Joan, the SNP, Scottish Government, as well as a range of economics experts, support."