Chancellor George Osborne has insisted that there remains a strong economic case for retaining the United Kingdom.
On a visit to Glasgow, Mr Osborne rejected the notion that Unionism was about "wallowing in nostalgia" and claimed Alex Salmond's plan to keep the pound as an independent nation was not credible.
He cited the eurozone as an example of a currency union that had run into difficulties because it was not accompanied by a political union.
In a speech to business leaders setting out the economic case for voting no in the 2014 referendum, Mr Osborne said he wanted to tackle head-on the argument that the British nation-state was a spent force.
He said: "Today the advocates of independence argue that Britain's value to Scotland is spent, that union is no longer in Scotland's economic interests and that those who continue to believe in Britain are wallowing in nostalgia.
"I want to take this argument head-on. I make no apology for sharing all of the instinctive emotional attachment to Scotland's place within the UK. Our shared history and culture, distinct yet intertwined identities, a whole greater than the sum of its individual parts.
"And I reject the idea that while Britain has a glorious history, it has little relevance in tackling the challenges and grasping the opportunities of the modern world."
He added: "In a world in which a separate, independent Scotland wished to pursue divergent economic policies, what mechanism could there be for the Bank of England to set monetary policy, as it does now, to suit conditions in both Scotland and the rest of the UK?
"As Chancellor of the Exchequer, I have seen no such credible mechanisms proposed by those advocating independence. I am not clear they exist.
"If the Scottish Government cannot provide answers to these basic questions about Scotland's currency, then the Scottish people are entitled to ask this basic question in return: what path is the Scottish Government leading them down?"
Mr Osborne was in Glasgow to speak at the annual Confederation of British Industry Scotland (CBI) dinner.
A spokesman for Scottish Finance Secretary John Swinney said: "Scotland needs no lessons from a Tory Chancellor whose disastrous economic policies are threatening jobs and investment across this country.
"And it simply beggars belief that Mr Osborne can claim the economy is healing on the same day that the OECD has downgraded its forecasts and predicts the UK economy will shrink by 0.7% this year.
"The uncertainty being caused to Scottish businesses is through Mr Osborne's policies and his Government's failure to invest in capital projects.
"The cast-iron position is that an independent Scotland will keep the pound, a position that Scottish Secretary Michael Moore has agreed with.
"And Scotland urgently needs the powers of an independent country to boost economic recovery and create jobs, and many of the leading job-creators in Scotland agree with us on that."
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