Labour claimed her position did not make sense and the Tories said Scotland would not be in a position to demand a seat on the powerful monetary policy committee (MPC).
The row broke out yesterday following an exchange between Ms Sturgeon and Scottish Labour's deputy leader, Anas Sarwar, on BBC Scotland's Big Debate programme on Sunday.
First Minister Alex Salmond has said an independent Scotland would keep using the pound and Mr Sturgeon was asked by Mr Sarwar how it was credible to have a foreign country set Scotland's interest rates, spending limits and borrowing limits.
Ms Sturgeon said that although there was no Scottish representation on the MPC at the moment it was "something that would change if Scotland was independent and in addition we'd get the fiscal levers that we don't have".
No political party has representation on the MPC but the Chancellor nominates four external members of the nine-strong committee currently headed by Bank of England Governor Sir Mervyn King.
Ms Sturgeon claimed a Scottish Finance Secretary "could appoint somebody as well and give Scottish representation that we do not have just know".
Shadow Scottish Secretary Margaret Curran said: "Nicola Sturgeon's latest position doesn't make any sense. Bald assertions won't win many converts to her cause and shows the SNP are just making it up as they go along.
"But there is a more profound question. If Scotland leaves the UK, but the UK then sets our currency, interest rates, borrowing levels, fiscal rules and monetary policy until such a point until Scotland joins the euro, why on earth would that be better?"
Tory finance spokesman Gavin Brown said: "One of the biggest risks to Scotland maintaining its triple A status is allowing Nicola Sturgeon to comment on the econ- omy. This is yet another economic gaffe from her and the SNP."
A spokesman for Ms Sturgeon said: "The cast-iron position is that an independent Scotland will keep the pound. There is no prospect of joining the euro in the short or medium term, and as the position of Sweden makes clear, no member state of the EU can be made to join the single currency. In terms of the Bank of England's monetary policy committee, the Deputy First Minister was merely repeating her previously reported suggestion that it would be entirely reasonable for an independent Scottish Government to appoint someone to the MPC in exactly the same way as the UK Chancellor currently does."
Meanwhile, a political analyst has claimed Alex Salmond has a mountain to climb to overturn poll ratings and win an independence referendum.
Peter Kellner of YouGov was referring to the poll his organisation conducted last week for Alistair Darling of the pro-Union campaign showing 57% opposed to independence and only 33% in favour on the eve of the Yes campaign launch.
He said: "The mountain Salmond must climb is even higher than those figures suggest," pointing to past experience in constitutional polls where there tends to be a swing back towards the status quo in the later stages. "To have a good chance of winning a referendum on independence in 2014, I reckon Salmond should be aiming for the 'yes' lead, as recorded by polls in the weeks leading up to the campaign, to be approaching two-to-one."