The campaign battle over Scottish independence took a bitter turn on Saturday when a senior nationalist warned businesses such as BP that they could face punishment for voicing concern over the impact of secession.
With the fate of the United Kingdom on a knife edge, the economic future of Scotland has become one the most fiercely debated issues less than six days before Scots decide on whether to break away.
Nationalists accuse British Prime Minister David Cameron of coordinating a scare campaign by business leaders aimed at spooking voters while unionists say separation is fraught with financial and economic uncertainty.
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But former Scottish Nationalist Party deputy leader Jim Sillars went much further than separatist leader Alex Salmond, warning that BP's operations in Scotland might face nationalisation if Scots voted for secession on Sept. 18.
"This referendum is about power, and when we get a 'Yes' majority we will use that power for a day of reckoning with BP and the banks," Sillars, a nationalist rival of Salmond's, was quoted by Scottish media as saying.
"BP, in an independent Scotland, will need to learn the meaning of nationalisation, in part or in whole, as it has in other countries who have not been as soft as we have been forced to be," Sillars said.
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When asked about the comments in a BBC radio interview on Saturday, Sillars confirmed he had raised the prospect of nationalisation but said he had used the term to get media coverage and that nationalisation was not on the table.
A spokesman for BP declined to comment. A spokeswoman for the Scottish nationalists could not be reached for comment.
The boss of BP, Bob Dudley, has said that Scottish independence could cause his company "uncertainties" and that he did not want to see Scotland drifting away.
"The heads of these companies are rich men, in cahoots with a rich English Tory Prime Minister, to keep Scotland's poor poorer through lies and distortions," Sillars was quoted in Scottish media as saying. "The power they have now to subvert our democracy will come to an end with a 'Yes'."
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In an extraordinarily strong attack on business, Sillars also said banks such as Standard Life would face tougher employment laws after a vote for independence.
Major banks, oil companies and supermarkets have said that a vote for secession would create concern: North Sea oil would have to be divided up while there is uncertainty over the future currency and central bank of an independent Scotland.
Deutsche Bank said a vote for independence would be a mistake akin to Winston Churchill's decision to return the pound to the Gold Standard or the failure of the Federal Reserve to provide sufficient liquidity to the U.S. banks, decisions that helped bring on the Great Depression.
"These decisions - well-intentioned as they were - contributed to years of depression and suffering and could have been avoided had alternative decisions been taken," David Folkerts-Landau, Deutsche's chief economist, said in a note to clients.
"Foreign investors come to Scotland because they rely on a predictable investment environment. All of this comes from a united Great Britain."
Such is the gravity of the situation that finance minister George Osborne, Britain's second most powerful man, cancelled a trip to the G20 meeting in Cairns which takes place the weekend after the vote.
Bank of England Governor Mark Carney will leave the G20 meeting early to be back in Britain in time for the vote. The central bank has plans in place for a possible secession vote.
Investors pulled $27 billion out of UK financial assets last month - the biggest capital outflow since the Lehman crisis in 2008 - as concern mounted over the fate of the United Kingdom, a report by London-based consultancy CrossBorder Capital showed.
Until September, all polls but one in 2013 had shown the unionists with a comfortable lead but several surveys this month show the nationalists have won over hundreds of thousands of Scotland's 4 million voters.
Emotions are high.
Horrified at the prospect of the breakup of the United Kingdom, thousands of loyalists from Northern Ireland and Scotland marched through central Edinburgh.
Armed with drums, flutes, banners, bowler hats and orange sashes, loyalists, named for their allegiance to the British throne, said the vote threatened their culture.
"It's your own history being taken away from you. What will you tell your grandchildren?" said Jim Prentice, a gardener wearing a Rangers soccer club shirt who had travelled from south of Glasgow to join the march.