NICOLA Sturgeon will today unveil a stimulus package aimed at boosting waning confidence in the economy following Britain's decision to quit the EU.

In an unprecedented step for a First Minister, the SNP leader will attempt throw down the gauntlet to the UK Government by pledging new infrastructure spending in a bid to create jobs and unveiling a support package for businesses.

It is understood that spending on NHS improvements will form a key plank of today's announcement while an investment plan already responsible for £6 billion worth of major projects is to be backed with new cash. Developments already in the pipeline will be brought forward.

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The bold move comes in response to growing alarm in the private sector over the impact of June's EU referendum result, which saw the UK vote to Leave despite 62 per cent of Scottish voters opting for Remain. Ms Sturgeon, who has pledged to do all she can to protect Scotland's relationship with Europe, yesterday met a German minister in Berlin for talks on her "next steps", would could include moving for a new independence referendum.

An influential think tank yesterday warned that Britain's economy slammed into reverse last month amid the fall-out from the Brexit vote, predicting a 50/50 chance of a new recession over the next 18 months.

The National Institute of Economic and Social Research estimated that GDP fell by 0.2 per cent month-on-month in July. For the three months to July, it said the economy eked out growth of 0.3 per cent in a "marked economic slowdown" on the second quarter, when GDP increased by 0.6 per cent. Meanwhile, the Institute for Fiscal Studies today paints a grim picture of the risks associated with the UK's post-Brexit future, saying maintaining membership of the single market could be worth an extra four per cent of GDP with tax receipts to be heavily hit under alternatives.

Some business leaders have called for measures such as new train lines to cut journey times from Scotland to London and upgrades to key roads such as the M8.

Construction of a rail link at Glasgow Airport, funded with City Deal cash should be fast-tracked to offset the economic uncertainty of the Brexit vote, according to council leaders who are calling on the transport minister to give the project his "full backing".

When announcing her package, Ms Sturgeon is expected to call for the UK Government to follow suit "urgently" in a move that would allow the Scottish Government to do more to accelerate capital spending. The Scottish Government had already said it plans to use new borrowing powers to fund infrastructure investment for the first time this financial year.

She will say: "The EU referendum outcome has created deep and widespread uncertainty. The UK Government has not yet taken a single meaningful step to alleviate that uncertainty, so the Scottish Government is taking early action to boost confidence, stimulate economic activity and reassure business.

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"We will supplement our Infrastructure Investment Plan, which is already delivering major improvements with £6 billion of projects currently under construction, with new spending this year to accelerate planned projects and support jobs.

"And we'll put in place new arrangements to engage with businesses to shape policy and provide up-to-date information and advice. These measures will help support new and existing jobs and alleviate business concerns at this difficult time."

Calls to speed up a infrastructure projects came after Neil Amner, president of the Glasgow Chamber of Commerce, said Brexit should be used as a "catalyst" for increased and more innovative infrastructure investment.

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The leaders of Glasgow and Renfrewshire councils will urge SNP ministers to accelerate City Deal-funded infrastructure schemes such as the proposed Glasgow Airport link at a meeting next month to counterbalance the fallout from the EU vote. It is estimated that projects associated with the City Deal will boast the region's economy by £2.2 billion and generate 15,000 construction jobs.