Scottish independence: Danny Alexander in post-Yes currency vow
The chief secretary to the Treasury has insisted he will continue to oppose a currency union even if Scotland votes for independence.
Danny Alexander told a BBC referendum debate in Inverness that such a deal would leave Scotland with less economic freedom than it has now.
But SNP MP Angus Robertson described a formal arrangement to share the pound as "eminently sensible".
He said it was the best of a "range of options" open to Scotland.
Earlier this year, Mr Alexander joined Chancellor George Osborne and Labour's Shadow Chancellor Ed Balls in ruling out entering into a formal currency union with an independent Scotland.
An unnamed UK government minister was quoted in the Guardian newspaper as saying "of course" a currency union would happen.
Better Together head Alistair Darling has been quoted as saying a deal would be "logical" and "desirable" for an independent Scotland - while arguing that it would ultimately lead to a return to a political union.
Mr Alexander was asked by an SNP councillor in the debate programme audience whether he too would begin arguing in favour of Scotland having a currency union if there was a "Yes" vote in September's referendum.
He responded: "No I won't be, because I think a currency union wouldn't work for an independent Scotland.
"If you join a currency union, what you are doing is you are giving up the ability to set your own interest rates, you are giving up your ability to have a currency that moves in value according to your own economy and in a country that will be much more dependent on oil and gas, with a price that fluctuates day by day as we know, that would have big effect on our economy that we couldn't adjust.
"And, as we have seen from the eurozone, in a currency union you would have to bind your hands on tax and spending.
"So in many ways Scotland would have, under those arrangements, less economic freedom, less economic sovereignty, less ability to affect our own economic destiny than we have at the moment."
Mr Alexander also predicted that continuing to use the pound without a formal currency union would be a "disaster" for an independent Scotland.
But Mr Robertson told the audience that all of the currency options open to Scotland after independence had been looked at in great detail by an advisory group to the Scottish government.
He added: "The report is more than 300 pages long and it goes through all of the options, but the best option for Scotland after a Yes vote is a continuing currency union.
"It is to the advantage of Scotland and Scotland's economy, and it is also to the advantage of the economy of the rest of the UK and for that reason it seems eminently sensible that after a Yes vote there is a currency union.
"We also know that senior people on the No side also agree that is what is likely to happen because we are able to read it across the front page of the Guardian newspaper, with a senior minister saying a currency union is indeed what would happen.
"The threats that we are hearing from the No side are all to try and scare people who are undecided or not certain about whether they should vote Yes."
Actor Ken Stott, who supports independence, told the debate he could foresee a time when there would be a separate Scottish currency, but said a currency union would offer stability while Scotland "found its feet" in the first few years of independence.
Better Together campaign director Blair McDougall accused the SNP of failing to give "straight answers" on what its alternative plan would be if there was no formal currency union.
The fifth panel member, writer and broadcaster Nicky Marr - who describes herself as an undecided voter - said she found it difficult to know which side to believe on currency.
Among the other topics tackled by the panel were the future of the Scottish NHS in the event of a "No" vote and London mayor Boris Johnston's call for Scotland not to be given any more powers if it rejects independence.
And Mr Alexander and Mr McDougall dismissed claims on social media that a major oil find in the Clair Field off Shetland had been hushed up by the UK government until after the referendum.
The rumours have circulated on Facebook and Twitter since Prime Minister David Cameron visited Shetland last month.
Mr Alexander said the allegations were "nonsense", while Mr McDougall pointed out that the prime minister had tweeted a picture of himself with a Shetland pony while on the islands.
He added: "If this was some sort of low-key secret agent, he was the worst James Bond we have ever had".
Mr Robertson - a regular user of Twitter - said he had not seen the reports.