Around 200 business leaders have backed Scottish independence in an open letter.
It comes the day after a group of 130 company leaders insisted that the case for leaving the UK "has not been made".
The signatories, led by Stagecoach chairman and SNP donor Sir Brian Souter, includes Clyde Blowers boss Jim McColl and retired William Hill chief executive Ralph Topping.
Published in The Herald newspaper on Thursday, the letter reads: "We are involved in business and entrepreneurship at different levels in Scotland and around the world. We believe independence is in the best interests of Scotland's economy and its people.
"We will gain the powers to give our many areas of economic strength even more of an advantage in an increasingly competitive world. There will be more opportunities for our talented and determined young people to stay and succeed here in Scotland."
The letter says that the "real possibility of a British exit from the European common market" is the biggest threat to Scottish business.
"We believe Westminster governments do not and never will pay sufficient attention to the interests of Scotland's economy," it said.
"The tax raids on our oil industry and pension funds by Labour and Conservative-led governments are clear examples of a short-term focus rather than a long-term strategy. Scottish industry is so often treated as a cash cow rather than a strategically important part of a more prosperous and a fairer society.
"The real threat to Scotland is the real possibility of a British exit from the European common market.
"Scotland must look outwards to the world of opportunity that awaits us. A Yes vote is the business and jobs opportunity of a lifetime for this and future generations."
The letter written on Wednesday by pro-Union business leaders highlighted the "uncertainties" they believe surround leaving the UK as they argue that "by continuing to all work together we can keep Scotland flourishing".
The group included Weir Group chief executive Keith Cochrane, Audrey Baxter, of Baxters Food Group, and Boyd Tunnock.