THE SNP will demand Holyrood control over all policy areas apart from defence and foreign affairs if they hold the balance of power after the election, Nicola Sturgeon has confirmed.

The First Minister yesterday backed comments by Alex Salmond, who said the SNP would insist on "real home rule" or "devo-to-the-max" as the price of a power-sharing deal with a minority Labour government.

Mr Salmond insisted devo-max - which would put Holyrood in charge of all domestic policy in Scotland including taxation - had been promised by the pro-UK parties in their pre-referendum "vow" to extend devolution.

Willie Rennie, the Scottish Lib Dem leader, accused Mr Salmond of being "sleekit" by misrepresenting the vow, which set out a timetable for "extensive new powers for the parliament".

Ms Sturgeon and Mr Salmond's move also reopened the debate about an independent or fiscally autonomous Scotland's economic prospects.

Under devo max, Scotland would rely on North Sea oil revenue to fund public services.

According to the Treasury, the collapse of oil prices to $50 per barrel would blow an £18.6billion black hole in the country's finances from 2016 to 2019, compared with Scottish Government forecasts.

Mr Salmond is aiming to return to Westminster as MP for Gordon at the general election.

Yesterday he said his party was not campaigning for a second independence referendum but "to deliver what was promised to us".

He said: "It is real home rule, devo-to-the-max or as near-federalism as we can get in the UK - that is what was promised and what should be delivered."

He added: "Home rule is control of all domestic affairs and taxation.

"Reserved to Westminster would be foreign affairs and defence.

"There is massive evidence that's what Scotland wants.

"This election is about delivering to Scotland what was promised.

"Not a referendum but what was promised in the referendum and the things that people are entitled to see."

Ms Sturgeon's official spokesman said she supported Mr Salmond's comments.

Asked whether she believed the vow amounted to a promise of devo max, he said: "Yes. That was explicit.

"The picture painted was a very clear one: Scotland votes No, Scotland gets devo max."

Mr Rennie, whose party holds the Gordon seat targeted by Mr Salmond, said: "Alex Salmond is sleekit.

"He used to say that home rule was independence now he's inaccurately redefining it again to promote an ultra-extreme form of devolution that would inevitably lead to the break-up of the United Kingdom."