Sturgeon grilled over fiscal policy, as she accuses other parties of reviving Project Fear

There were heated exchanges as Labour leader Jim Murphy, the Conservative's Ruth Davidson and Liberal Democrats' Willie Rennie sought answers on how the SNP would cover the £7.6 billion spending gap that economists have suggested Scotland would face if it took control of its own fiscal affairs.

Ms Sturgeon told BBC's Sunday Politics Scotland programme that full fiscal autonomy would take several years to implement but with new powers Scotland would start growing its economy and revenues.

She said: "This week we've seen the Project Fear that dominated the referendum revived by these three unionist parties, trying to talk down Scotland and assert that we're not capable of running our own affairs.

"This is a debate about whether Scotland should take more control over our own economic decision-making. Do we take proper control over our finances or do we leave ourselves at the mercy of Westminster's continued cuts?"

Ms Davidson told programme host Gordon Brewer: "I don't think we can accept Nicola saying 'this is Project Fear 2, this is three other parties ganging up on me, ganging up on the Scottish Government and ganging up on Scotland'.

"This (the figure) didn't come from us. You're right in saying this came from the Institute for Fiscal Studies. It also came from a group of Scottish-based economists that projected the gap to be bigger.

"You can't say 'I want control, I just don't want it yet', and then blame us for the fact that your sums don't add up."

Mr Murphy said: "As is often the case, Nicola makes a dreadful point in a very reasonable way.

"She's making this up as she goes along. To make this £7.6 billion up Scotland would have to grow at twice the rate of the rest of entire advanced world, so how would you do that Nicola? What's the magic policy you have that the rest of the world doesn't have on this issue?"

Mr Rennie said the SNP is in an "even deeper hole than before" after dropping a planned corporation tax cut under former leader Alex Salmond.

He said: "They have no answers."

During the debate Ms Sturgeon asked the Labour leader "in billions, how many more cuts is Labour going to introduce?"

Mr Murphy said: "We have a different view. You're thinking like a Tory. There's different way out of this. You don't just have to cut your way out of a deficit. We grow our way out of the deficit."

The SNP leader responded: "You've just made my argument for me. If you're going to grow your way out of deficit, you need the powers to do it."

Questioned about the prospect of another vote on independence, Ms Sturgeon reiterated that, for another referendum to feature in a future SNP manifesto, "something would have to change" and people would have to vote for it.

She said: "I am not planning another referendum right now, there is not another referendum on the cards."

Ms Davidson said: "You've got a conference coming up in September, you've got 80,000 new members that might be popping along to that. Are you going to put a motion at your conference on this, to put a referendum into your next manifesto?"

The First Minister said that "before people vote in 2016, they'll know the position of the SNP".

Commenting after the debate, Labour's shadow Scottish Secretary Margaret Curran said Ms Sturgeon "must come clean on her party's plans to borrow billions to pay for their policy of full fiscal autonomy".

She said: "During the debate Nicola Sturgeon did not dispute the Institute for Fiscal Studies assessment that full fiscal autonomy would cost Scotland £7.6 billion a year in tax revenues. She was asked at least eight times if an SNP government would borrow its way out of a deficit before she conceded they would have to.

"Yet she still claims that Scotland, uniquely amongst the nations of the developed world, would achieve heroic growth levels in excess of 5% to make up the short fall.

"The truth is the SNP are engaged in 'Project hide the facts' from the people of Scotland on the real costs of their policies."

The SNP said Mr Murphy had "collapsed" under questioning on cuts.

The party's election campaign coordinator Angus Robertson said: "The problem for Jim Murphy and the Labour Party is that for as long as he dodges the question on cuts, voters simply will not trust him or his party.

"His entire strategy seems to be about avoiding the question instead of being honest with the public.

"And as Mr Murphy has now conceded, the SNP position that the best way to tackle a deficit is to grow your way out of it - not impose draconian cuts, even though more cuts remains Labour's policy. His position is increasingly indefensible."

Ms Davidson said after the debate: "We've taken important steps to sort out the economy so that we don't land massive debts on our children, but Nicola Sturgeon wants to undo all that hard work.

"She says she wants to slam the economy into reverse - borrowing billions for future generations to pay.

"It is clear Nicola Sturgeon doesn't care about safeguarding our country's finances, and is threatening to make huge borrowing a key part of any deal with the Labour Party."

Mr Rennie said the SNP leader had "broken a promise the size of Ben Nevis" on another referendum.

He said: "People need to know whether their vote for the SNP this time round will trigger a referendum in the SNP's manifesto in 2016. Nicola Sturgeon's refusal to answer this basic question makes clear that Scotland faces neverendum.

"It matters because during the referendum we know the SNP took their eye off the ball. As a result, public services were neglected.

"We have seen from Canada the economic impact of an uncertain constitutional environment. Quebec lost jobs and wealth. That damaged the province in the long term. I want a Scotland which builds a stronger economy and a fairer society, balancing the books and delivering more powers."