THE SNP will press for devo max as soon as possible after the General Election, Nicola Sturgeon has declared, as opponents warned of deep spending cuts if the country had to rely on its own taxes.

Official figures yesterday showed Scotland was £12.4billion in the red in the last financial year, 2013/14.

Scots contributed £400 per head more in tax to the Treasury than the UK average but benefited from an extra £1200 in public spending.

The figures indicated Scots would have been £800 per person worse off under devo max, prompting stark warnings about the constitutional set-up from Labour, the Conservatives and Lib Dems.

But Ms Sturgeon said: "The figures tell us nothing at all about how Scotland would perform with greater economic and fiscal powers.

"Short of independence I believe we should have full fiscal autonomy and we will continue to argue that case.

"I'd like it to start as soon as possible.

"If the SNP has got significant clout in the next Westminster Parliament then we will be arguing for a strengthening of the Smith Commission proposals that leads to a position where the parliament is fully autonomous in terms of our economic and fiscal position."

The figures were revealed in the Scottish Government's annual Government Expenditure and Revenue report, known as GERS.

It showed Scotland was deeper in the red than the UK as a whole. Scotland's deficit amounted to 8.1 per cent of gross domestic product compared with 5.6 per cent across the UK.

The state of Scotland's finances, compared with the UK, worsened since the previous year as oil revenues fell.

Scotland's share of North Sea taxes fell to just under £4billion, down from £5.2billion in 2012/13.

Oil revenues accounted for £9.7billion in 2011/12, the last time Scotland was in a stronger financial position than the UK as whole.

Figures for the current financial year are expected to show an even sharper fall in North Sea revenues as a result of plummeting global oil prices.

The Fiscal Affairs Scotland think tank predicted Scotland's deficit was set rise to £13.9billion.

Under current UK Government spending plans, the shortfall would shrink to £5billion by 2020, though Scotland would remain deeper in the red than the UK as a whole throughout the period, according to FAS.

Ms Sturgeon insisted a fiscally autonomous Scotland would be in a better position to reduce the deficit by growing the economy.

In the short term, she suggested the Scottish Government would borrow to maintain public spending, rather than imposing cuts or increasing taxes.

Under devo max, Scotland's borrowing levels would have to be negotiated with the UK Government.

Jim Murphy, the Scottish Labour leader, said Scotland under devo max would face "austerity max" to balance the books.

He said: "The SNP Government's own figures confirm their plan for full fiscal autonomy would mean cuts on a scale never before seen in Scotland.

"Today's figures confirm that only Scottish Labour can credibly claim to be Scotland's anti-austerity party."

Scottish Conservative finance spokesman Gavin Brown said: "The main point to take from this is, as part of the UK, Scotland is part of a family where everyone puts in and shares the proceeds.

"That security was jeopardised last September, and it's the SNP's sole, stated aim to jeopardise it again in May.

"The SNP wants full fiscal autonomy, and as we can see from these figures that would mean absolute chaos for Scotland's finances."

Alistair Carmichael, the Lib Dem Scottish Secretary, said: "Today's figures from the Scottish Government put the case for remaining in the UK beyond all doubt."

Scottish Trades Union Congress General Secretary Grahame Smith said: "Today's report is a sobering reminder of some of the risks of full fiscal autonomy for Scotland."