JIM Sillars has called for SNP MPs to back the Prime Minister’s Brexit deal on condition referendum powers are transferred to Holyrood along with a raft of economic levers.

The former SNP deputy leader – who backed leaving the EU – said as the third biggest party at Westminster, the SNP could used its influence.

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Asked if he thought his party could do more to exert leverage on the minority Tory government, he said: “What about looking for the need for more powers for Holyrood. On tax, for example. On income tax, we only have power over pay as you earn.

"We don’t have any power over dividend payments and capital gains tax nor do we have power National Insurance contributions. So yes – ask for a package of new powers – including the right to decide when to have a referendum. But also further economic powers – that would be a good trade off and I would back that.”

He said the demand for referendum powers to be given to Holyrood went further than the request for a Section 30 order, which would narrow the Scottish Government options on the timetable for a second independence vote.

“It’s different from a Section 30. If you have a Section 30, you are committed to an early referendum ... but if we had the powers over referendums we could decide on the issue of timing whenever we decide,” he added.

Asked if this was still possible, he said: “I don’t think so The SNP doesn’t think like that. They took a line from day one and have never veered from it, to condemn the [EU referendum] result. I don’t think they have made anything out of it.”

He added: “If they had taken a more positive position toward the vote they would have been able to get more. From day one after the referendum, the SNP threw away any influence they could have had.”

But SNP MP Tommy Sheppard disagreed, saying the party had made compromise suggestions to May, including pressing her for a special deal for Scotland. According to the Scottish Government plan in December 2016, Scotland would remain in the single market and have further devolution – including immigration powers.

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Sheppard said: “Jim is coming from his position that he thinks Brexit is a good thing when pretty much everyone else in the SNP thinks Brexit is a bad thing, whether we are in the UK or not in the UK. The second thing is, we have tried to exercise leverage, we have tried to offer compromises.

“But we have been met by a government that is completely intransigent and is occupied only with shoring up a fleeting Tory party unity and is not interested in building a genuine political consensus. Over the past couple of years every time the Scottish Government or SNP has suggested compromise, it has been thrown back in our faces.

"Thirdly, specifically we have argued that f we couldn’t get what we wanted for the UK, then we wanted a differentiated settlement for Scotland. We put that forward but were treated with contempt.”