The stand-off over what currency an independent Scotland would use continued last night with neither side willing to give an inch.
The bitter row was triggered by announcements from the three main parties at Westminster that they would not sanction a currency union.
The Conservatives, Labour and Liberal Democrats stepped up their calls for First Minister Alex Salmond to reveal his Plan B now that his preferred option of using the pound, and relying on the Bank of England to bail Scotland out of trouble, had been rejected.
Former chancellor Alistair Darling, head of the pro-union Better Together campaign, called the SNP leader “a man without a plan”.
Referring to an interview in which the first minister said the Scottish Government’s fiscal commission had set out a “range of options”, Mr Darling said: “The penny has dropped for Alex Salmond – he knows he cannot promise the pound.”
He added: “The SNP’s fiscal commission set out these options but only set out a plan for a currency union.
“Now that option is off the table there is no currency plan. Alex Salmond needs to get his Cabinet together urgently to prepare a new plan.”
Mr Salmond said he would continue to argue for a sterling area due to the benefits for both Scotland and the rest of the UK as well as the “misrepresentations” by his opponents.
“We will continue to articulate that because we think the unionist position will fragment because it is against the interests of Scotland and against the interests of business in the rest of the UK,” he said.
“Business does not want to pay transaction costs to trade with Scotland and it won’t have to under our sterling area proposal.”
Scottish Conservative enterprise spokesman Murdo Fraser said: “Alex Salmond can’t credibly continue saying a currency union is his sole tactic. Everyone who would have a say in this from the UK side has blown it out of the water.
“The time has now come to examine alternatives, and that can’t just be this ludicrous idea of having a Panama pound.”