NICOLA Sturgeon has said her government could drop its support for a third runway at Heathrow airport, potentially jeopardising thousands of jobs in Scotland.

The First Minister said the 2016 policy was now under review because of the “climate emergency” threatening humanity.

It follows Ms Sturgeon ditching her SNP manifesto pledge to give the air industry a £150m tax cut to reduce carbon emissions from flights.

The review could result in the collapse of a Memorandum of Understanding the Scottish Government signed with Heathrow in October 2016.

SNP ministers backed the expansion on the basis that it would boost Scotland’s economy more than a new runway at London Gatwick or a new airport in the Thames estuary.

In return, Heathrow committed it to the creation of up to 16,000 new jobs across Scotland resulting from the new capacity, Glasgow Prestwick Airport potentially becoming a logistics hub; £200m of construction-related spend in Scotland; and a  £10m route development fund.

Heathrow also promised a “significant, long term marketing campaign at Heathrow to promote all that Scotland has to offer”.

At the time, then SNP economy minister Keith Brown said: “Building a third runway at Heathrow provides the most significant benefits to the country’s economy and connectivity.

“Heathrow’s plan offers significant job creation, major investment opportunities and, crucially, seeks to address how all of Scotland’s airports benefit from the new runway capacity.”

When the issue went to a vote in the Commons last year, SNP MPs abstained, and the Heathrow expansion was passed 415 to 119.

However last month, at the SNP conference, Ms Sturgeon declared a climate emergency to help avoid runaway climate change, and a review of government policies affecting carbon emissions and the environment.

This week’s ditching of a promised cut in air passenger duty was a “first step”, her government said.

At First Minister’s Questions, Scottish LibDem leader Willie Rennie asked if the government would not also drop its support for Heathrow’s third runway to reduce carbon emissions.

She replied: “We will require to look at all of our policies across all areas of Scottish Government responsibility through that new lens of climate change.

“So whether it’s the policy that Willie Rennie cites today, or any other policy, that’s the commitment that we are making.”

The First Minister’s official spokesman later confirmed support for Heathrow was under review, and that the Memorandum of Understanding could therefore be affected.

He refused to say if SNP MPs might in future oppose legislation related to the runway, saying the issue was “hypothetical”.   

He said: “To be clear what we are talking it about, it is not within the gift of the Scottish Government whether a third runway is built at Heathrow or not.

“That Memorandum of Understanding was about the jobs that would bring to Scotland.

“The decision in principle, just to reiterate, is not one for the Scottish Government.”

Asked about a review of Prestwick International Airport, which the Scottish Government owns and keeps afloat through tens of millions of pounds of loans, he said: “I've got no update on that in terms of reviewing financial(s). If the inference is we are suddenly going to pull the plug on Prestwick, then No. Prestwick is a piece of national infrastructure.”

Later, at the SNP’s EU election launch, Mr Brown said he was unaware of Ms Sturgeon’s statement and referred questions to the government, as he was no longer a minister.

Mr Rennie later urged Ms Sturgeon to withdraw support for the Heathrow runway.

He said: “The SNP have now admitted that their long-standing policy to offer up huge tax cuts to airlines would damage the environment and seriously hamper our chances of achieving our climate change targets. They were right to U-turn on it.

“But now that it’s dawned on them that hundreds more flights won’t be good for our climate they must next withdraw their misjudged support for expanding Heathrow.

“The SNP backed that without even bothering to calculate the impact it would have on Scotland's environment.

“Wherever the emissions are happening they will hurt our climate.”

Tory MSP Murdo Fraser said: "This is an irresponsible U-turn which could jeopardise the creation of thousands of jobs.

“The SNP needs to remember why it backed this project in the first place.

“But because of Nicola Sturgeon’s game-playing with the environment, the economy in Scotland could lose out badly.”

A Heathrow spokesperson said: “Heathrow Expansion is not a choice between the economy and the environment - it will deliver on both.

"Heathrow is committed to ensuring that Scotland benefits from the airport’s expansion and we will continue working with Scottish businesses and politicians to boost domestic connectivity, as well as deliver the jobs and economic growth that expansion is set to bring.

“At the same time, we agree with the First Minister that achieving a global goal of net zero carbon, including aviation, by the middle of the century, is essential to avoid the worst effects of climate change.

“Heathrow will work with partners to innovate, invest and incentivise to make our contribution.”