The Scottish Government's Nobel prize-winning economic advisers have been challenged to reveal whether they support the SNP's threat to withhold an independent Scotland's share of the UK national debt if Westminster rejects a currency union.

Crawford Beveridge, chair of the Scottish Government's Council of Economic Advisers and its fiscal commission working group (FCWG), is giving a lecture to Glasgow Caledonian University on Monday.

He was challenged to reveal the group's opinion on the SNP's debt threat by Conservative finance spokesman Gavin Brown at Holyrood today.

Finance Secretary John Swinney repeated ministers' insistence that Scotland should not shoulder a share of the debt if the UK Government starts "seizing the assets of the UK", namely the pound and the backing of the Bank of England.

SNP MSP Kenneth Gibson, convener of Holyrood's Finance Committee, quoted one expert who suggested that Scotland "should be compensated for all of the oil money" the Treasury has taken.

Mr Brown said: "I've read the FCWG reports, I've read their published statements, I've read the minutes of their meetings, and I haven't been able to trace anywhere a specific comment from that group saying that they all think that that is a logical, intelligent or even a correct thing to do.

"I understand that the chair of the FCWG will be giving a keynote speech on Monday of next week.

"I ask the Scottish Government again, in that keynote speech, will there be a firm statement made publicly by the Scottish Government that every member of their working group support that argument?

"Because if they do not, they are standing pretty much by themselves. Economists have pointed out that that is not a logical position to take. Even economists who support independence cannot support that particular assertion and claim made by the Scottish Government."

Mr Swinney said: "Mr Brown should just look at what the fiscal group have said.

"What the Government has set out is that if the UK Government is going to advance an argument which is about seizing the assets of the UK and not engaging in a fair distribution of the assets between the rest of the UK and Scotland, then why on earth should an independent Scotland take on its appropriate share of debt, which we are perfectly prepared to take on?

"Given that the UK Government is prepared to act in such a reckless fashion, that is the consequence of the recklessness of the UK Government."

Mr Brown challenged Mr Gibson to say whether anyone giving evidence to the Finance Committee supported the Scottish Government's debt threat.

Mr Gibson said the position had the support of Professor David Simpson, a Harvard-educated economist who has worked for the United Nations, World Bank, European Commission and Standard Life.

He added: "Indeed Dr Jim Cuthbert said Scotland should be compensated for all of the oil money they have taken out of Scotland over so many years."

Scottish Labour finance spokesman Iain Gray said: "As long ago as December, the economist David Owen at Jefferies Limited told us that walking away from debt would raise the cost of borrowing by 5%. Investment would be hit, public finances would suffer and mortgages would go up.

"What's more, membership of the EU requires a currency and a central bank. So a sterlingised Scotland would not be able to stay in the European Union.

"But the most irresponsible thing about this currency car crash is that the potential victims are not the banks and businesses of Scotland, but ordinary Scots."

He added: "There is nothing more fundamental to economic opportunity than a stable economic base, nothing more fundamental to that than a stable currency.

"No matter how glittering the image the Cabinet Secretary asks us to dream of the opportunities of independence, as long as he has no answers on currency his whole proposition has feet of clay."