Alex Salmond is facing fresh calls to set out his 'plan B' on currency if a deal cannot be agreed that would allow an independent Scotland to retain the pound.
Shadow business secretary Chuka Umunna yesterday became the latest pro-Union campaigner to demand to know what alternative options there could be if Scots vote to leave the UK in next month's referendum.
Former chancellor Alistair Darling has already pressed the Scottish First Minister on the issue in their first TV debate, while former Scottish Enterprise chief executive Jack Perry is also demanding answers.
Mr Umunna said the issue of what currency an independent Scotland would use was creating a "lorry-load of uncertainty for Scottish businesses and Scottish people".
He spoke out as he visited the HQ of Omega Diagnostics Group in Alva, Clackmannanshire. Mr Umunna argued that while businesses required certainty to invest and grow, the September 18 independence vote was creating doubt.
"All businesses I meet across the UK like certainty and strive to see more of it, because that gives them the confidence to invest and plan for the future," he said.