Scotland's business community has taken centre-stage in the independence campaign today as 130 company chiefs insisted the case for leaving the UK ''has not been made''.
Business leaders have signed an open letter highlighting the ''uncertainties'' that surround leaving the UK as they argue that ''by continuing to all work together we can keep Scotland flourishing''.
The companies are said to employ 50,000 people in Scotland, with signatories including Weir Group chief executive Keith Cochrane, Angus Cockburn, interim chief executive of Aggreko, and Victor Chavez of Thales UK.
Audrey Baxter, of Baxters Food Group, and Boyd Tunnock are also among those who have put their name to it .
UK Government minister Danny Alexander said the letter had come from "t he very people who create the wealth and jobs that our prosperity depends on".
The Chief Secretary to the Treasury said: "The signatories run small and large firms in every part of Scotland, employing tens of thousands of people.
"I urge everyone in Scotland, particularly those who are still undecided on how to vote, to take the opinions of these wealth creators seriously."
Despite that, former William Hill chief executive Ralph Topping said the "smart money is on a Yes vote" in next month's referendum as he revealed he has donated £50,000 to the pro-independence campaign.
Mr Topping said he was one of about 150 business leaders who had signed a letter in favour of Scotland leaving the UK, which is to be published later this week.
The former betting company boss said while a " number of business leaders have spoken out in favour of Westminster", there were many who supported an independent Scotland.
He added: " I am one of them. Our voices, too, should be heard just as loudly.
"My wife and I have therefore decided to make a donation of £50,000 to the Yes campaign because the underdog deserves the support it needs to win as the race tightens even more after Monday's debate.
"I am proudly featuring in a letter of around 150 business people supporting Yes to be published later this week. The big gamble for Scotland is staying with Westminster. The smart money is on a Yes vote."
Some 130 business leaders all signed the open letter in favour of the union in a personal capacity, with it stating that, as part of the UK, Scotland's economy is growing, with high employment and record investment.
The letter highlighted the ''uncertainties'' that surround leaving the UK and claimed that ''by continuing to all work together we can keep Scotland flourishing''.
The company chiefs said: ''As job creators, we have looked carefully at the arguments made by both sides of the debate. Our conclusion is that the business case for independence has not been made."
As the letter was published, former chancellor Alistair Darling was reunited with his one-time boss, former prime minister Gordon Brown, on the referendum campaign at a rally in Dundee.
With Scots starting to vote by post from today, Mr Brown argued that it was the shareholders of the country's most profitable companies who would benefit from independence.
The former prime minister said that while the nationalists "dine out" on ideas of equality, they have "no plans to raise funds that would come from a fairer taxation system".
He also claimed SNP plans to cut corporation tax would benefit large companies, including energy firms.
"The biggest beneficiaries of the SNP's tax policy are the shareholders and directors of the privatised energy companies in Scotland," Mr Brown said.
"The beneficiaries of an independent Scotland are not the ordinary people of Scotland but the richest directors of the most profitable, privatised companies in Scotland.
"When you look at the Scottish National Party policies, inequality and poverty will survive until doomsday if Alex Salmond is all that confronts it."
The former prime minister delivered his rallying call for the union despite being heckled by a member of the audience.
The man, who was reported to have given a false name to gain entry to the event at Dundee's Caird Hall, shouted "rubbish" and "you're an absolute disgrace" before he was removed from the meeting midway through Mr Brown's address.
The rally, which came as people who have chosen to vote by post in the September 18 referendum receive their ballots, saw Mr Brown and Mr Darling share the stage despite well-documented disagreements in the past.
Meanwhile, nationalists called on Mr Brown and his former chancellor to "co me clean and admit that there is no guarantee of further job-creating powers in the event of a No vote".
SNP Westminster finance spokesman Stewart Hosie pressed the issue after the First Minister challenged the Better Together leader over what powers could come to Scotland if voters reject independence.
Mr Hosie said: "F ollowing Alistair Darling's complete failure to outline any further powers that would come to Scotland in the event of a No vote, people are waking up to the fact that the only thing guaranteed by a No vote would be more Westminster austerity.
"That is why it is vital Scotland votes Yes, because that is the only way we can achieve the job-creating powers needed to build a more prosperous and fairer society."