NICOLA Sturgeon was left floundering after appearing to forget how much setting up an independent Scotland would cost – just two weeks after her own report placed the figure at £450 million.

The First Minister repeatedly failed to answer when quizzed during a television interview on the first day of the SNP's conference in Aberdeen. 

After being asked about the issue six times, she eventually conceded: "I can't recall the exact figure in the report."

It comes as Ms Sturgeon will today contrast the “shambolic” Conservative government with the SNP's record in Scotland. 

She will argue the Tories' hostile migration policy is having a disastrous impact on public services and the economy – and ramp up calls for powers over migration to be devolved to Holyrood.

Addressing delegates, she is expected to say: “Scotland is a welcoming country – our prosperity and our public services depend on it.

“If Westminster cannot or will not act in our best interests, it is time that our own parliament was able to do so. It’s time for powers over migration to come to Scotland.” 

The SNP's Growth Commission report, which was launched at the end of last month, said the total set-up costs to establish government departments and agencies after independence would be "around £450 million over five years". 

It cited analysis by Professor Patrick Dunleavy of the London School of Economics, and argued most of these costs would be associated with establishing four new bodies – a defence force, a foreign affairs and trade department, a security agency and a central bank and regulator.

But in an interview with Channel 4 News, Ms Sturgeon was repeatedly unable to remember this figure, insisting: "We haven't gone through the process of analysing the report and coming to a recommendation". 

Despite this, she argued it was "realistic". The First Minister was also unable to recall the £200m cost of setting up a Scottish social security agency.

She told Channel 4's reporter: "I don't have all of those figures right at the tip of my fingers right now."

A Scottish Conservative spokesman branded the interview an "embarrassment". 

He said: “This is where the SNP's broken case for independence lies: with Nicola Sturgeon unable to remember fantasy figures for set up costs from a report she still insists is credible. What an embarrassment.

"No wonder pro-independence supporters as well as pro-Union backers are running a mile from her independence blueprint. Everyone can see it doesn't add up.”

Scottish Labour's deputy leader Lesley Laird accused Ms Sturgeon of being "unable to answer even the simplest of questions on her report". 

The First Minister will use her speech at the SNP conference today to announce that the flagship £150m Building Scotland Fund – the precursor to the Scottish National Investment Bank which was unveiled as part of this year’s budget – is “open for business.”

She will reveal £70m is to be invested in the coming year, including £25m to support at least 3000 new homes. 

Ms Sturgeon will say: “Setting up a Scottish National Investment Bank is one of the most important steps that the Scottish Government is taking – it has the potential to put Scotland at the forefront of technological and environmental innovation and create jobs.

“Of course, it will take a couple of years to get the bank up and running - so to bridge the gap, we have announced £150m over the next two years for a new Building Scotland Fund.

“I can announce today that this Fund is now open for business."