Former chancellor Alistair Darling has poured scorn on Alex Salmond's claim that an independent Scotland could appeal to the Bank of England in a future financial crisis.

Mr Darling also accused the First Minister of admitting Scotland could not have bailed out RBS and other banks four years ago with his claim the London-based institution would be Scotland's "lender of last resort".

His intervention came as Scottish Labour accused the First Minister of jeopardising people's pensions, mortgages and financial future with the plan, which could also see the bank set Scotland's interest rates.

Mr Darling described the SNP leader's suggestion as "ludicrous". The remaining parts of the UK would never agree to their bank acting in such a role for a different country, he suggested. He told The Herald: "What could be more ludicrous than an independent Scotland where the reserve bank is in a foreign country? You could not do that without the permission of the rest of the UK."

He added: "Clearly this emphasises, whether we like it or not, Scotland would not have had sufficient funds to bail out RBS or HBOS – and this is an admission from Mr Salmond that this is the case."

Sir Menzies Campbell, the former Liberal Democrat leader, also questioned whether the bank would agree to play such a crucial role – to be prepared to offer credit when no-one else will – for another country.

"What on earth would persuade the Bank of England to be the lender of last resort for an independent government? You can't have your cake and eat it," he said.

At First Minister's Questions in Holyrood, Labour leader Johann Lamont accused the First Minister of taking "unneces- sary risks" by insisting the Bank of England would be the lender of last resort.

She said: "The reality is the First Minister is telling us he is content to have the key decisions that will impact on people's mortgages, savings and pensions made by a foreign bank with no remit to look at Scotland's conditions and circumstances.

"It is unclear to most Scots why he is prepared to take unnecessary risks with our mortgages, savings, pensions in the midst of the worst economic global crisis since the 1930s.

"John Swinney has already admitted his plans will mean him going to the Bank of England to ask permission on how much he can borrow, what his fiscal policies will be and how much he can spend. That does not serve our national interest."

However, Mr Salmond hit back saying a British chancellor would be "biting our hands off" for an independent Scotland to keep the pound. He said oil and gas reserves and the value of Scottish exports, such as whisky, meant an independent Scotland would benefit a "sterling area" of countries if it left the UK but retained the pound.

Mr Salmond added there were 67 countries using another nation's currency "either in formal or informal monetary unions at the present moment".

"That doesn't mean they're not independent countries, that just means they're in monetary unions," he added.

The row followed comments made by the First Minister during a keynote speech on independence in London.

The SNP leader told an invited audience that in a monetary union the lender of last resort would be the Bank of England.

Often seen as the final defence against disaster, a lender of last resort plays a crucial role in preventing the collapse of banks considered to be "too big to fail".

A spokesman for the Bank of England refused to comment on whether it was technically pos-sible for the institution to act as a lender of last resort to an independent Scotland or whether it would be prepared to do so.