Theresa May has hit out at Nicola Sturgeon’s post-Brexit independence push, accusing the First Minister playing down the effect of a plunge in the global price of oil.

No 10 criticised Ms Sturgeon’s suggestion over the weekend that wealth was less important for Scotland than self-governance.

In an article in the Sunday Herald to mark the second anniversary of the 2014 referendum, Ms Sturgeon wrote: "The case for full self-government ultimately transcends the issues of Brexit, of oil, of national wealth and balance sheets and of passing political fads and trends.”

The comments were seized on by other parties who accused Ms Sturgeon of advocating independence at any price.

Downing Street attacked the phrase "passing political fads".

A No 10 spokesman said: “I’m not sure you would describe Brexit, oil and the economy as ‘passing fads’. These are fundamental issues about what Britain is and what it is dealing with.”

A spokesman for the First Minister hit back, saying: "The Tories have caused the chaos of Brexit and are now utterly clueless about what to do next.As such, they are making the case for independence."

Nearly half, 46 per cent, of Scots oppose another vote in the next few years.

But a new survey, the Close Brothers Business Barometer, shows almost two in five small businesses in the UK – and more than half in Scotland - believe that Brexit will lead to Scottish independence..

As the row intensified ex-Better Together boss Lord Darling of Roulanish said Ms Sturgeon was in "no rush" to hold another vote, despite Alex Salmond’s prediction of a 2018 poll.

The former Labour chancellor said her remarks were designed instead to throw “red meat" to supporters by hinting at a second referendum.

"Nothing has changed since 2014, “ he told the BBC Good Morning Scotland programme, “... roughly speaking 45 per cent of the population would vote for independence, 55 per cent would vote against it.

"If (Ms Sturgeon) loses, she knows she would be finished. That's why she is in no hurry to rush into it.

"What she has got to do, of course, is to continually throw red meat to her supporters.”

Former former first minister Mr Salmond rejected Lord Darling’s claim that nothing had changed as he stood by his autumn 2018 forecast.

Instead of starting "at 27 per cent of the vote, which is what we did in 2012, Nicola Sturgeon will be starting or would be starting it at 48 per cent or 49 per cent of the vote," he said.

Westminster could stop a referendum by allowing Ms Sturgeon “to secure Scotland's position within the (EU) Single Market without having an independence referendum.”

But it did not have the “flexibility, the sensitivity, the democratic acknowledgement of Scotland's rights to do that”, he predicted.

Former Lib Dem leader Paddy Ashdown said he believed Ms Sturgeon would “play it long” but added: “If we arrive at a solution other than access to the (EU) Single Market, her hand will be strengthened.”

Some senior SNP figures want their party leader to wait until after a potential Conservative victory in the 2020 general election.

Today Scottish Economic Secretary Keith Brown will call for a multi—billion pound stimulus package for Scottish firms in the wake of the Brexit vote.

Scottish ministers have already announced plans to spend an extra £100 million, while the Bank of England has made billions of pounds available in support.

But Scottish ministers will say that an extra £5 billion of infrastructure spending could bring £400 million to Scotland and support 3,000 jobs..

Mr Brown said that the help should be announced “in the Autumn Statement as a minimum, but ideally in shorter order than that".

MSPs are set to debate the issue later today.

Meanwhile, manufacturing leaders EEF will today warn that Brexit will fail unless British companies can still hire thousands of EU workers.

The warning comes as Mrs May tells the international community that the UK has to be able to control its borders.

The UK Government is under increasing pressure to set out who will be able work in Britain after Brexit and who won't.

Mrs May has already shot down calls for an Australian-style points system backed by high-profile Vote Leave campaigners, including the new Foreign Secretary Boris Johnson, amid concerns it would have no upper limit on the numbers coming the UK.

Meanwhile, fresh fears emerged that many of the UK's largest banks could relocate to Germany.

In an interview the head of Germany''s central bank Jens Weidmann warned that if the UK quit the European Economic Area it would automatically lose ‘passporting’ rights that allows the City of London to work across Europe.