Nicola Sturgeon has predicted Alistair Darling, the No campaign leader, will argue for a currency union following a Yes vote.

The Deputy First Minister said she was "absolutely convinced" the former Labour chancellor would perform the U-turn.

Last week Mr Darling said the move would make "no sense for Scotland and no sense for the UK". His comments came as the three main pro-Union parties joined together to rule out a "sterling zone" with an independent Scotland.

However, the SNP has accused Labour, the Liberal Democrats and the Conservatives of "campaign tactics" in the run-up to September's referendum.

Ms Sturgeon said many Unionist politicians would change their views if people in Scotland backed independence.

"Once people decide then they have decided, and that calms (things) down at lot," she said.

She said that after a Yes vote "politicians in England will want to make sure the negotiations are good for England.

"Likewise, politicians from Scotland who are on the opposite side of the debate from me at the moment will (after the vote) be on the same side (as me).

"And Alistair Darling will argue for a currency union, I'm absolutely convinced of it".

A Better Together spokesman said: "I think Nicola Sturgeon has been taking a leaf out of Alex Salmond's book and sticking her fingers in her ears so she can't hear anyone saying anything she disagrees with. The currency union is dead in the water."

Yesterday, Scottish Secret­ary Alistair Carmichael called on business leaders to press the SNP for "credible answers" over currency.

Speaking to the Institute Of Directors in Aberdeen, Mr Carmichael said he was "heartened" more Scottish businesses were speaking up and asking questions.

At Holyrood, Ms Sturgeon defended the Scottish Government's position on the currency and EU membership as MSPs clashed for the first time since returning after their February recess.

She said it was an "affront to democracy" that a senior UK Government source claimed a Yes vote might not lead to independence under the timescale outlined by the Nationalists.

Questioned about the claim, revealed in The Herald last week, she said: "It is a travesty of democracy, an affront to democracy and a sign of growing panic at the heart of the No campaign."

She accused the UK Government of ignoring the Edinburgh Agreement, the deal paving the way for a legally recognised referendum that committed both Governments to work constructively in the interest of people north and south of the border.

Ms Sturgeon also ruled out joining the euro currency as she was pressed on European Commission President Jose Manuel Barroso's warning that an independent Scotland would face a "difficult if not impossible" task negotiating entry into the EU.

She said remaining outwith the euro would be a "red line" for the Scottish Government in any membership talks but insisted no country could be forced to join against its will.

Ms Sturgeon again claimed an independent Scotland would be able to agree a pound-sharing deal with the rest of the UK, despite Chancellor George Osborne ruling out the proposal last week.