Speaking to an audience in the US on Friday, Salmond said there was now no need for a "fiscal stabilisation pact", with the Bank of England and the Treasury setting rules for sharing sterling, despite saying the opposite six months ago.
Former Labour chancellor Alistair Darling accused the First Minister of flip-flopping on a central issue of the independence debate.
The pact, which Salmond had advocated, would have seen an independent Scotland agree limits for taxes, spending and borrowing with the UK Government as part of arrangements for a cross-border "sterling zone". Crucially, it would have capped Scotland's ability to borrow from the market, so its national debt would not balloon and undermine the pound.
Despite going against the Nationalist grain, agreeing a fiscal policy with London was seen as a worthwhile trade-off for monetary union and having the Bank of England act as a lender of last resort.
Floating the idea in January this year, Salmond told The Economist magazine: "I'm in favour of a stability pact."
In a BBC interview in March, he said: "You'd need a fiscal stability arrangement for a monetary union.
"Let's say your stability pact said over the long term your borrowing should not exceed 3% of GDP.
"I would argue that's no more than the fiscal discipline a sensible country would have in any case."
But after a speech at the Chicago Council on Global Affairs, Salmond changed tack. Answering a question about restrictions flowing from monetary union, such as the Bank of England setting interest rates for Scotland, he said: "I don't believe that a monetary policy restriction would have to have a fiscal stabilisation pact. I think we can have plenty of room for manoeuvre within a currency union."
Professor John Kay, one of Salmond's former economic advisers, said there was "not a cat's chance in hell" of Scotland securing a monetary union with sterling without a strict fiscal pact, adding: "It all sounds like bluster. They don't know what they're doing and they haven't thought it through."
Darling, chairman of the pro-Union Better Together campaign, said: "In Alex Salmond we have a man who is quite prepared to tell the people of Scotland one thing, only to go behind their backs and tell people around the world something entirely different. He simply has to come clean. This is not an issue that can be left blowing in the wind."
LibDem leader Willie Rennie added: "This throws the SNP's policy into confusion. To use the pound, an independent Scotland would have to live by the UK's rules."
In a US newspaper interview last week, Salmond also reversed his position on the independence referendum, accepting there would be only one question, not two.
A spokesman for the First Minister said: "The Scottish Government recognises the need for fiscal discipline. The point the First Minister was making, and has consistently made, is that Scotland is in a stronger financial position than the UK as a whole, and therefore will have no difficulty adhering to fiscal discipline within a sterling zone as an independent country."
Alex Salmond, March 2012 on the BBC
"You'd need a fiscal stability arrangement for a monetary union... There would have to be a stability pact which would have criteria on what you could borrow."
"I don't believe that a monetary policy restriction would have to have a fiscal stabilisation pact. I think we can have plenty of room for manoeuvre within a currency union."