A senior figure in the SNP has questioned Scottish Government analysis which found a so-called 'no deal' Brexit would cost Scotland £12.7 billion a year by 2030, describing such forecasts as "very, very dubious".
Former Scottish Government minister Alex Neil, who voted leave in the EU referendum, said there are "so many unknowns" surrounding the figures in the economic forecast paper, launched by Nicola Sturgeon on Monday.
The paper models three possible Brexit scenarios which the First Minister said were the "only realistic outcomes of Brexit" - staying in the single market and customs union, a preferential trade agreement or reverting to World Trade Organisation terms in a no-deal Brexit.
Researchers analysed the impact on GDP, trade and immigration and found the latter deal could cost everyone in Scotland £2,300 by 2030, a £12.7 billion loss to the economy, while staying in the single market would cost around £4 billion or £700 per head.
The First Minister said if the UK does leave the European Union then remaining in the European single market and the customs union is the "only option that makes sense".
Mr Neil told the Daily Telegraph that a senior economist had informed him that in terms of long-range economic forecasts it would be hard to accurately predict "what will happen in the next three months".
The former health minister said: "That sums it up. I'm not saying we should not do these projections but you get out of the model what assumptions you put into it.
"I think until we see the shape of the deal, we don't know what the assumptions are.
"The point is you can never treat economic forecasts as a label for the truth because the reality is forecasts are very, very dubious, particularly when there are so many unknowns."