Scotland's Deputy First Minister Nicola Sturgeon has said that a currency union makes sense for the UK as much as it does for an independent Scotland.
Speaking on Sky News' Murnaghan, she said that members of the 'No' campaign were casting doubt on the issue as a scare-mongering tactic.
She was speaking ahead of the publication on Tuesday of a "landmark document" which sets out the "economic, social and democratic" case for independence.
A currency union under which an independent Scotland shared the sterling with the UK "wouldn't work," according to the Scottish Secretary.
Speaking on BBC One's Andrew Marr Show, Alistair Carmichael said independence is about "political disintegration" rather than integration.
He joined the Better Together campaign leader Alastair Darling in calling on the nationalists to reveal their "plan B" for the currency of an independent Scotland.
Scotland's Deputy First Minister Nicola Sturgeon has revealed March 24th 2016 as the proposed independence date and previewed the country's "blueprint" for the future.
Ms Sturgeon said the 670-page document, which is due to be published on Tuesday, will "set out the social, economic and democratic for independence" and reveal "how Scotland will become independent":
Alastair Darling, head of the anti-independence Better Together campaign, has called on the separatists to "come clean" about their vision for an independent Scotland.
He told Sky News' Murnaghan that the option of Scotland entering into a currency union with the UK is "beginning to look like a non-starter" and that the SNP had to reveal its "plan B".
Scotland Secretary Alistair Carmichael said the referendum on Scotland's independence "is a very real danger to the future of the United Kingdom".
Mr Carmichael told the BBC's Andrew Marr Show, "I've been given this job ... and it's probably the most important job in politics for the next 12 months".
Deputy First Minister Nicola Sturgeon described the landmark guide to an independent Scotland "the most comprehensive and detailed blueprint of its kind ever published".
She said it sets out the economic, social and democratic case for independence.
– Deputy First Minister Nicola Sturgeon
It demonstrates Scotland's financial strengths and details how we will become independent - the negotiations, preparations and agreements that will be required in the transition period from a vote for independence in September next year to our proposed Independence Day of 24th March 2016 and in time for the first elections to an independent Scottish Parliament in May of that year.
...It illustrates how the powers of independence can be used to benefit individuals, families, communities and the nation as a whole - and it answers a range of detailed questions that we have been asked.
March 24, 2016, could be the date Scotland becomes independent from the UK if voters back the move in next year's independence referendum, the Deputy First Minister has announced.
The date is included in the Scottish Government's white paper, described as a "blueprint" for independence, which will be published on Tuesday.
Deputy First Minister Nicola Sturgeon said it is a "landmark document" which has economic growth, jobs and fairness at its heart.
The 670-page document runs to more than 170,000 words and will be available as a hard copy and as an e-book.
Ms Sturgeon said it will be the document that drives the independence debate, providing the positive case for a vote in favour of independence.