The SNP needs to look again at its position on sharing the pound with the rest of the UK after independence as it failed to win the economic debate in the run-up to the referendum, an activist has said.

George Kerevan said that, while nationalists had had the better economic case, they failed to convince many middle-class professionals.

Economic issues took centre stage in the run-up to this historic vote in September, with pro-UK campaigners attacking Scottish Government plans for a currency union with the rest of the UK.

Mr Kerevan conceded: "I don't think we actually won the economic argument during the referendum. I think we had the best case but I think many people, particularly the professional middle-classes, didn't quite get it.

"And I'm going to say this very gently - I think the party may have to revisit its position on the common currency."

Mr Kerevan spoke out in a debate on the economy at the SNP annual conference in Perth, where he branded the UK economy "truly disastrous" and called for "criminal" bankers to be jailed.

He told the conference the UK currently has a "disastrous economy whose banking system is an organised criminal conspiracy".

He added, to cheers: "Incidentally, I hope when we send a bus-load of new MPs down, one of the first things we do is get a vote together to change British law so we can put those criminal bankers in jail."

But he used his speech to argue for Scotland to get full control of the economic levers of power.

"Scotland has to take control of the economic levers, otherwise when the UK economy goes down under the waves we will go with it," he said.

"We need to save Scotland, we need economic levers.

"It's not just the case that we want income tax (powers), it's not just the case that we want the Smith Commission to give us control over social welfare provision - those things will be a poisoned chalice unless we get control of the economic levers."

The conference backed a call for substantial economic powers to be included as part of the further devolution that was promised by all the UK parties in the run-up to the referendum.

SNP MSP Kenneth Gibson, who is also convener of Holyrood's Finance Committee, said: "Scotland is one of the wealthiest nations in the world, with an abundance of natural resources and human talent. But Westminster's obsession with austerity and cuts has meant that all too often we can't make the most of our wealth - and instead we face cuts that hit society's poorest people hardest.

"The Scottish Government is doing all it can to boost Scotland's economy with the powers we currently have - and as a result we have seen record levels of employment in the face of the Westminster parties' sustained economic mismanagement.

"With further powers over the economy, welfare and taxation, we can strengthen and grow our economy, ensuring we are better equipped to tackled poverty and inequality and undo some of the damage of Westminster cuts.

"In the days leading up to the referendum, the Westminster parties made a 'vow' to the people of Scotland to deliver extensive new powers - and people expect this to be delivered. Substantial new economic powers must be among these."