Scotland would face an "enormous challenge" to produce their own currency if it became independent, according to the chair of HSBC, Douglas Flint.
He said: "Scotland would be faced with monetary policy implementation without representation - a very odd form of independence."
The three main parties at Westminster have all ruled out the Scottish Government's preferred option of a formal currency union between an independent Scotland and the rest of the UK.
The Scottish referendum vote will take place on September 18.
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