Comments from an academic who used to advise the Scottish Government “demolish” the economic case for independence, the Conservatives and Lib Dems have said.

The pro-Union parties seized on remarks from Professor Mark Blyth, who formerly sat on the Government’s advisory council for economic transformation.

The Brown University political economist spoke at the Festival of Economics event organised by a group called Scotonomics – one of whose founders is former SNP Aberdeen city councillor, Kairin Van Sweeden, who now sits as an independent.

The SNP say there is “overwhelming” evidence that other European countries outperform the UK economically.

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In a discussion with the event’s hosts, Prof Blyth was critical of certain aspects of the arguments for Scottish independence, with clips of his comments being shared on social media.

In one, he said: “I fully understand the desire to be separate, but the idea that this isn’t gonna hurt – ooft.

“You can’t really say that Brexit is the worst thing ever then commit the biggest Brexit of all time. Which is literally what this is.

“So if you’re going to think about this, being independent, you’ve got to think very sensibly about what this means and how you’re going to develop income-generating assets to pay for stuff.

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“Why? Because at the end of the day as a small, open economy, which you then will be, you need to balance your imports and your exports over the long term, or everyone thinks your currency is s***e.”

Investors dumping an independent Scotland’s currency could lead to a “mini-Argentina” scenario, he said.

At another point, he said: “Scotland, particularly in nationalist circles, likes to say that Scotland is a small, open economy like the Nordic economies.

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“That’s a bit like saying I’m a supermodel because I also have legs.”

The SNP and other proponents of independence have often pointed to Brexit as a reason Scotland would be economically better off leaving the UK and rejoining the EU.

However, Prof Blyth has previously attacked such arguments – suggesting in 2021 that economic upheaval from independence would be “Brexit times 10”.

Reacting to his comments from the weekend, the Tories’ economy spokeswoman Liz Smith said: “This is a devastating demolition of the economic case for independence by a former adviser to the SNP Government.

“It’s an evisceration of the absurd and baseless reassurances from Nationalists that tearing Scotland out of the UK would somehow be pain-free.

“The reality is that an independent Scotland would lead to a hard border with by far, our greatest trading partner, and put our entire economy, which is already stagnating under the SNP’s high-tax regime, at risk.”

Scottish Liberal Democrat economy spokesperson Willie Rennie said: “It’s bad enough for the SNP that their economic case for independence has been demolished by a leading academic but for it to be demolished by a leading academic that the SNP leadership endorsed is devastating.”

However, the SNP’s depute leader, Keith Brown, said the case for independence has never been stronger.

He said: “The evidence is overwhelming that other independent countries in Europe like Ireland, Norway and Sweden are all fairer, wealthier and more productive than the UK – so, with all our advantages and talents, why not Scotland?

“With people across Scotland paying the heavy price for broken Brexit Britain and no Westminster party offering any alternative, the case for independence has never been so strong.

“Whether it’s cruel and incompetent Tory governments or being dragged out of the EU against our will, Scotland is suffering by decisions taken in Westminster that ignore our interests.”

The Scottish Government’s Energy Minister Gillian Martin attended another event at the Scotonomics conference.

She said: “The energy transition is an area in which we are going to potentially not even have the population capacity to deal with the amount of jobs that are going to be out there.”