THE SNP’s support for a second EU referendum has come under fire from the party’s longest-serving MP.

In a rare attack on Scottish Government policy, Pete Wishart warned backing the so-called People’s Vote risked seriously undermining a successful Yes campaign in the future.

READ MORE: Pete Wishart: This is why backing a People’s Vote is a bad idea

“Then there is precedent. There is now a view amongst the politicians leading the ‘People’s Vote’ campaign that all big constitutional referendums should now have a ‘confirmatory’ second vote,” he writes in The National today.

“The politician with perhaps the highest profile in the People’s Vote campaign, Vince Cable, has explicitly said that a confirmatory vote would be required on a successful independence referendum.

“By enthusiastically buying into this ‘confirmatory’ vote for an EU referendum we weaken our hand in resisting unionist calls for a second vote on a successful indyref. You can just imagine the unionist chorus – ‘you were all for a second confirmatory vote on the EU but not one for independence’?”

“And if they were successful in using this precedent against us, unreconciled unionists would be working non-stop from the day after the referendum to ensure that a successful outcome would be overturned. Every apparatus of state would be deployed and they would ensure that the worst possible ‘deal’ would be offered to the Scottish people in the hope that their union could be rescued.”

The SNP MP, who is shadow leader of the House of Commons and is chair of the Scottish Affairs Select Committee, criticised Nicola Sturgeon for supporting a second EU referendum without getting any guarantees a repeat of a remain vote in Scotland would be respected if the UK as a whole voted again to leave. He also suggested the campaign behind the second EU vote was essentially pro-Union in stance with little interest in protecting Scotland’s position.

“No one from the People’s Vote campaign has attempted to answer the question, which is – what if Scotland votes to remain (which it will) and the UK as a whole votes to leave again (which it might)? They won’t answer because, for them, it is a UK vote and the outcome in Scotland is irrelevant ...They simply do not acknowledge we as a nation have our own national view and national interest,” he said. “To say we will sign up to a referendum without any guarantee that our Scottish national voice will be at least acknowledged is little more than an open invitation to have our national view ignored and disrespected all over again. We are simply inviting all the indignities we are currently enduring to be replicated and refreshed. “

He added he wanted to see Brexit reversed and believed independence would be easier to achieve if the UK was in the EU as it would mean there would be no hard border between the new state and the UK.

Earlier this month the FM said SNP MPs would back a second EU referendum in a Commons vote. She indicated her party would seek a guarantee if Scotland voted again to remain while the rest of the UK voted to leave, it would not be forced to accept the result a second time.