A central part of the SNP's general election campaign has been based on "fiddled figures", Labour has claimed.

Kezia Dugdale, the party's Scottish deputy leader, said while nationalists wanted full fiscal autonomy, economic analysis from the Scottish Government had still included money Holyrood receives from Westminster under the Barnett formula.

Ms Dugdale told the First Minister: "The SNP's economic credibility is in tatters."

She added that that Scottish Government economic paper had been "torn apart" by experts and claimed the nationalists had "a general election plan based on fiddled figures".

Full fiscal autonomy would see the Scottish Government having to raise enough in taxes to cover all the money it spends on public services, with Labour adding that the block grant Scotland receives from Westminster each year would be axed as a consequence of this.

That would leave Scotland some £7.6 billion worse off, according to Labour, with Ms Dugdale insisting: "It's clear that when the numbers don't add, this First Minister makes them up anyway."

Nicola Sturgeon branded the attack as "desperate stuff from a dying Scottish Labour Party" as she again stated that economic modelling in the Government's research "doesn't simulate the continuation of the Barnett formula"

On the SNP's demands for Holyrood to have greater control of the economy, she said: "We don't want to sit back and accept continued Tory and Labour cuts, we want to have responsibility in Scotland to have an alternative to that, to grow our economy, to get the benefits of economic growth that we can invest in our public services."

The First Minister told Ms Dugdale: "I know Labour's position is that they think the best way to protect Scotland's public finances is to continue to allow Westminster governments, including Tory governments, to run those finances.

"But the experience of that for Scotland over the past few years has not been a particularly good one because the Westminster government has cut the budget of this Scottish Government by 10% in real terms.

"If that's what Kezia Dugdale and Labour wants to defend, and defend the additional £12 billion of cuts for Scotland that are coming down the track from Westminster, then let them do that.

"I suspect their poll ratings would continue to plummet as a result."

Ms Dugdale pressed Ms Sturgeon on the issue at First Minister's Questions as Labour revealed it had written to the chair of the UK Statistics Authority (UKSA) complaining that economic analysis from the Scottish Government had failed to follow its code of practice.

Labour finance spokeswoman Jackie Baillie in a letter to Sir Andrew Dilnot said: "There is a particular obligation on ministers and the Scottish Government to uphold the standards set by the UKSA."

She stated that there were no contact details on the Scottish Government's economic analysis paper and that the paper had also failed to state which method of economic modelling the research had relied on, citing both of these as breaches of guidelines.

Labour also highlighted comments from economics expert Professor Brian Ashcroft, who said in his blog that the economic model had been "used inappropriately to suggest political economy outcomes that are fanciful and are lacking in economic rigour".

Prof Ashcroft also claimed that the Scottish Government economists were "effectively assuming full fiscal autonomy plus Barnett" in the paper.

But he stated: "Elementary political economy tells us that with full fiscal autonomy Barnett would be abolished and there would be no risk pooling or sharing of revenues between the rest of the UK and Scotland."

Labour finance spokeswoman Jackie Baillie claimed at a briefing that the SNP's "proposal for full fiscal autonomy is falling apart".

She added: "We think essentially the First Minister, whether knowingly or otherwise, has absolutely misled Parliament, because the assumption that Barnett remains is just not on."

She accused the Government of attempting to "hide the truth that there would be a huge, big £7.6 billion black hole of the centre of the SNP's plans for full fiscal autonomy".

Ms Baillie went on: "Not only did they mislead Parliament I think they are misleading the people of Scotland, who have a right to know what the choices are that face them when they go to vote on May 7."

Ms Dugdale said: "The SNP Government's analysis told Scots that although the general election policy is for full fiscal autonomy within the UK, which means what we can spend in Scotland we raise in Scotland, we can still benefit from the higher public spending that comes from Barnett and the block grant.

"That's not true. We know it and she knows it.

"I know the First Minister wouldn't have intentionally tried to mislead parliament when she suggested we can have full fiscal autonomy within the UK and keep Barnett money."

Ms Dugdale continued to press on the issue, saying: "The block grant sounds like a piece of dry political theory, but it couldn't be more important to the future of Scotland, for the sake of our NHS and schools, for the sake of our pensioners who have worked hard all their lives and deserve to enjoy their retirement in comfort.

"The SNP's economic credibility is in tatters. The impartial Institute for Fiscal Studies say the SNP plans for full fiscal autonomy would cost Scotland £7.6 billion.

"The experts at the Scottish Parliament say cutting public spending by billions would cost 138,000 jobs and Professor Brian Ashcroft says the SNP's analysis is 'partial at best and dishonest at worse'."

But Ms Sturgeon told her: "The modelling doesn't simulate the continuation of the Barnett formula."

While she claimed Labour "would prefer to join the Tories and say Scotland is not capable of standing on our own two feet", she said the SNP wanted Holyrood to "to take our own decisions and to keep the benefits of the good decisions we make".

The First Minister argued: "I want us to be able to grow our economy, reduce the deficit in that way, rather than have a situation where we continue to be at the mercy of Westminster cuts."

She told MSPs: "My position is I want this Parliament to have more fiscal and economic powers so that we can grow our economy faster and reduce the deficit that Scotland currently carries.

"We don't want to sit back and accept continued Tory and Labour cuts, we want to have responsibility in Scotland to have an alternative to that, to grow our economy, to get the benefits of economic growth that we can invest in our public services."

Ms Sturgeon pledged: "This Government and the party I lead will continue to argue an alternative to the Tory-Labour austerity .

"We have the clear choice that confronts people at the election in just a few weeks time - they can vote for Labour and more Tory spending cuts to come or they can vote SNP for a clear, consistent and principled alternative to austerity."

With polls continuing to show support for the SNP well ahead of backing for Labour, the First Minister told Ms Dugdale: "I suspect I know which way it's going to go."

Conservative leader Ruth Davidson said the SNP had come "no closer to admitting how much full fiscal autonomy would cost Scotland".

She called for the Scottish Fiscal Commission, set up by the Scottish Government, to come up with a costing for the next five years before the general election.

"This is about how we fund every school, every hospital and every police officer," Ms Davidson said.

"The people of Scotland have the right to know in fiscal autonomy what it is that they are being asked to vote for."

Referring to Alex Salmond, she said: "So we have the 'not first minister' not in the chamber, swanning around the television studios of London, telling anyone who will listen how he will be running the whole of the UK, making statements over tax, welfare, defence and spending, and yet the current First Minister standing here is unable to say how she will fund public services.

"When will the SNP branch office rein in its foreign office?"

Ms Sturgeon said: "It is clear that my predecessor is frightening the life out of the Tories and Labour Party - long may it continue."

She said the fiscal position of Scotland had been set out in the GERS figures published recently.

"The UK is deeply in deficit and deeply in debt," she said.

"The difference between Kezia Dugdale, Ruth Davidson and me is this: I don't think we should simply sit back and accept the inevitability of continued deficits and austerity cuts.

"I think we should take control to do something about that."