Independence could cost Scotland’s economy £8 billion and jeopardise thousands of jobs, according to the Better Together campaign.
Leader Alistair Darling said businesses in Scotland could suffer if they are cut off from the UK’s single market by a Yes vote in the referendum.
Research on the so-called “border effect” shows that 247,000 Scottish jobs are dependent on cross-border trade with the rest of the UK, the campaign said.
The figure was published in an analysis by Brian Ashcroft, emeritus professor in economics at the University of Strathclyde, last month.
Mr Darling also pointed to a recent research paper by economists at Stirling and Edinburgh Universities which estimated that a new border would reduce Scottish economic output by 5.5%.This would be equivalent to £8 billion a year and would result in thousands of job losses, he claimed.
Historical analysis shows a drop in trade between previously united countries - such as the Czech Republic and Slovakia - was “typical” after separation, the campaign said.
Speaking at the launch of a new campaign office in Galashiels, Mr Darling said people in the south of Scotland were particularly concerned about the potential risks to cross-border trade and travel.
The former chancellor said: “The access to the single market of 63 million people in the UK rather than just 5 million in Scotland is good for Scottish jobs.
“This is particularly the case in the south of Scotland, where workers, families, products and services cross between England and Scotland several times a day without any restrictions or additional costs.
“Where is the sense in putting up barriers between Scottish firms and their customers in the rest of the UK?” “Breaking up the UK single market could cost the Scottish economy £8 billion, risking thousands of jobs. We don’t have to take that risk.”
A poll for ITV Border recently showed support for a Yes vote in the Scottish Borders and Dumfries and Galloway council areas at 26%, with No at 61% and 13% undecided.
Paul Fletcher, a member of the pro-independence group Business for Scotland, said: “The border effect that Scottish businesses are worried about isn’t the border between Scotland and England, it’s the border that the UK parties seem determined to put up between Scotland and the EU.”
‘With both Cameron and Miliband talking about having a referendum on staying in or leaving the EU, there’s a real danger that Scotland will be separated from a single market of some 500 million people and that’s a threat to business.
“What is clear is that Scotland needs to be part of the EU to take full advantage of the biggest single market in the world and the current direction of travel of the UK is towards the exit. Scotland needs independence to maintain our EU membershp and our business advantages in it.”
SNP MSP Chic Brodie said: “This is recycled nonsense from Alastair Darling and the No campaign, who are truly scraping the bottom of the barrel with these silly claims.”
“The No campaign is only embarrassing itself with its desperation to try and twist every statement and statistic to talk Scotland down.”