The Government has denied claims there could be a currency union between an independent Scotland and the rest of the UK.
An unnamed minister had reportedly told The Guardian that a deal on sharing the pound could be made with Scotland if the UK's nuclear submarine fleet was able to remain at Faslane.
But Chancellor George Osborne insisted that if Scotland opted for independence it meant "walking out of the UK pound".
The UK is keen to keep its nuclear submarines in FaslaneThe newspaper said the minister told them: "Of course there would be a currency union.
"There would be a highly complex set of negotiations after a yes vote with many moving pieces.
"The UK wants to keep Trident nuclear weapons at Faslane and the Scottish government wants a currency union - you can see the outlines of a deal.
George Osborne has denied there will be a currency union"Saying no to a currency union is obviously a vital part of the no campaign. But everything would change in the negotiations if there were a yes vote."
The Scottish Government's White Paper on independence, published in November 2013, states a shared currency is in the "economic interests" of Scotland and the rest of the UK.
However, in a joint statement with Liberal Democrat Treasury Chief Secretary Danny Alexander, Mr Osborne said: "There will not be a currency union in the event of independence. The only way to keep the UK pound is to stay in the UK.
"A currency union will not work because it would not be in Scotland's interests and would not be in the UK's interests."
Scottish Secretary Alistair Carmichael said: "An anonymous, off the record quote does not change the stark reality on the currency.
"The UK Government has listened to the views of the Governor of the Bank of England and the independent advice of the Permanent Secretary to the Treasury that a currency would be damaging for all the United Kingdom.
"That's why a currency union simply will not happen."
Nicola Sturgeon, Scotland Deputy First Minister, said the claims were a significant development in the referendum campaign.
She told Sky News: "The fact of the matter is a currency union makes sense, it makes sense for an independent Scotland but it would also make overwhelming sense for the rest of the UK as well.
"Trident will not be a bargaining chip for the Scottish government, we want to see nuclear weapons removed from Scotland as quickly as it's safely possible to do so."
A YouGov poll for The Times newspaper last week suggested 45% of Scots did not believe Chancellor George Osborne's pledge to rule out a formal currency union.