Alistair Darling has reiterated his call for the SNP to set out what an independent Scotland's economy would look like in a message to business leaders.
The head of the pro-union Better Together campaign warns in an article for the Institute of Directors, which will be sent to its members, that not enough information has been given to voters.
The former Chancellor said businesses across Scotland were concerned about potential trade barriers, the currency of a separate Scotland and future membership of the European Union in the event of a Yes vote in the referendum.
But the Scottish Government hit back, saying the threat to Scotland's EU membership came not from next year's independence referendum but from the in-out EU vote David Cameron has pledged to hold in 2017.
Mr Darling asks: "Would we have to join the Euro? Would we keep the vital opt-outs? Would we lose our rebate?
"Would we have to join the EU immigration system, which would mean that our immigration protocols would be different from those operated by our near neighbours south of the Border?"
"These are important questions that have yet to be answered by the Nationalists.
"I don't ask them to score political points. I do so because the answers are of fundamental importance to the future prosperity of Scotland, including our businesses."
"We need to know the answers to these and other legitimate questions. We cannot be asked to take the biggest decision in 300 years on the basis of the nationalists telling us not to worry, that everything is going to be all right on the night."
A Scottish Government spokesman said: "An independent Scotland will keep the pound.
"We will also remain part of the EU - and it is Westminster's proposed in-out referendum on EU membership that poses the only threat to Scotland's continued membership, with all the potential consequences for investment, jobs and the economy which that involves."
Why are you making commenting on The Herald only available to subscribers?
It should have been a safe space for informed debate, somewhere for readers to discuss issues around the biggest stories of the day, but all too often the below the line comments on most websites have become bogged down by off-topic discussions and abuse.
heraldscotland.com is tackling this problem by allowing only subscribers to comment.
We are doing this to improve the experience for our loyal readers and we believe it will reduce the ability of trolls and troublemakers, who occasionally find their way onto our site, to abuse our journalists and readers. We also hope it will help the comments section fulfil its promise as a part of Scotland's conversation with itself.
We are lucky at The Herald. We are read by an informed, educated readership who can add their knowledge and insights to our stories.
That is invaluable.
We are making the subscriber-only change to support our valued readers, who tell us they don't want the site cluttered up with irrelevant comments, untruths and abuse.
In the past, the journalist’s job was to collect and distribute information to the audience. Technology means that readers can shape a discussion. We look forward to hearing from you on heraldscotland.com
Comments & Moderation
Readers’ comments: You are personally liable for the content of any comments you upload to this website, so please act responsibly. We do not pre-moderate or monitor readers’ comments appearing on our websites, but we do post-moderate in response to complaints we receive or otherwise when a potential problem comes to our attention. You can make a complaint by using the ‘report this post’ link . We may then apply our discretion under the user terms to amend or delete comments.
Post moderation is undertaken full-time 9am-6pm on weekdays, and on a part-time basis outwith those hours.
Read the rules hereComments are closed on this article