THE SNP has been accused of putting party interests before Scotland's interests after confirming it will abstain on tonight’s crunch Commons vote on Heathrow’s third runway.

Alan Brown, the Nationalists' transport spokesman, claimed Chris Grayling, the Transport Secretary, had failed to provide detail over which Scotland to London routes would benefit from Public Service Obligations or which Scottish airports would be protected under PSOs to ensure they benefited from the new runway.

He also said a letter from the UK Government to Scottish MPs last week had failed to meet the ambitions previously set by the Scottish Government, nor had the UK Government set out the climate impact of increased aviation.

“Chris Grayling has completely failed to make the case for Scotland,” declared Mr Brown. “SNP MPs could not vote for a third runway at Heathrow with no guarantees of the benefits.

“The SNP wants the best deal for Scotland. Any Heathrow expansion plan must provide significant benefits to our economy and connectivity, yet Grayling failed to provide any real assurances or meet with me to give any guarantees.”

The Kilmarnock and Loudoun MP made clear the SNP would continue to work with Heathrow on the benefits that could be delivered but he insisted: “The UK Government has let Scotland down. The Tories can't be trusted to keep their own promises, never mind the promises they make to others.

“With Airbus and airlines set to depart Brexit Britain, a third runway could well find itself in a ghost airport; the UK Government should be turning their attention to getting the best possible deal when the UK leaves the EU which includes staying in the customs union and single market.”

But Luke Graham, the Scottish Conservative MP, hit out at the Nationalists, saying: "Heathrow expansion will bring huge benefits to Scotland yet the SNP have ignored that in order to pursue their agenda of disruption at Westminster.

“The idea they no longer support a third runway because Heathrow is about to become a 'ghost airport' is laughable, even by the SNP's standards."

The MP for Ochil and South Perthshire added: “They have put their nationalist interests before the national interest and they should be ashamed.”

His Tory colleague, Ross Thomson, who represents Aberdeen South, also hit out at the SNP's decision, saying the party was “letting Scotland and Aberdeen down”.

Earlier, Labour peer, Lord Adonis, who was Transport Secretary in Gordon Brown’s Government, tweeted: “What is SNP doing on Heathrow? Scotland needs bigger & better Heathrow - nearly two-thirds of business traffic from Glasgow & Edinburgh goes to London by plane because the trains so slow (despite my best efforts!) SNP shouldn’t play politics with this but do the right thing.”

In 2016, the Scottish Government came out enthusiastically for Heathrow expansion, saying it offered the “greatest strategic and economic benefits to Scotland,” creating up to 16,000 jobs and providing a significant boost to the nation’s air connectivity.

Last week, the UK Government said a third runway would result in:

*100 new weekly flights between Scotland and Heathrow;

*reserved slots for Scotland flights and

*new competition on existing routes, which could lead to lower prices for passengers.