DAVID Mundell should stand down as Secretary of State for Scotland over the Tory party’s £1 billion deal with the DUP, the SNP’s Pete Wishart has said.

Over the weekend the Tory minister was quoted in two different newspapers saying he would not “agree to anything that could be construed as back door funding to Northern Ireland.”

The MP even told the Sunday Post the deal Theresa May reached with the DUP to prop up his party’s minority government would be a“totally transparent arrangement”.

“I’m not going to agree to anything that could be construed as back-door funding to Northern Ireland, he added. “There are rules.The Barnett Formula is to Scotland’s advantage.

“I’m not going to do anything to prejudice it. Any funding that goes to Northern Ireland, then Barnett rules will ensure the appropriate funding comes to Scotland.”

Wishart said that despite those promises, the £1bn deal Theresa May agreed with Arlene Foster, showed that Mundell had either not stood up to the Prime Minister or allowed her to walk over him.

Wishart’s comments came as the Scottish Government called for a joint ministerial committee to investigate the DUP deal, saying that it has robbed Scotland and Wales of billions of pounds worth of Barnett consequentials.

Because the funding agreed between May and Foster was for specific projects, it does not affect the Barnett Formula, the calculation used to assess the change in Scotland’s block grant based on English spending.

However, the Scottish Government, argue that with the spending being specifically used to guarantee the votes of the DUP, and given that huge chunks of the money allocated is for general spending on health and infrastructure rather than targeted projects, that it really should have gone through Barnett.

According to Strathclyde’s Fraser of Allander institute that would have cost May’s government £30bn, and would have generated Scottish consequentials of £3bn.

Mundell told the BBC the deal did nothing to undermine the Barnett formula.

“I was very clear that any arrangement had to be absolutely transparent — it is. I was clear that it had to be subject to the Barnett rules — it is. I was also clear there should be no subversion of the Barnett rules, and that hasn’t happened.”

He added: “I always argue for resources and funds for Scotland and the most important argument that I’ve made consistently over the years is that the Barnett formula should continue, and that’s the difference between myself and the SNP.”

The Tory veteran also welcomed the Scottish Government call for a review, saying the result would show “that the position the government adopted is fully compliant with the rules.”

SNP MP Pete Wishart has said that it is clear from his first interview since the DUP/Tory deal that David Mundell “failed to lift a finger” to secure any more cash for Scotland through Barnett consequentials and that his position is now “utterly untenable”.

Wishart replied: ‘’David Mundell has broken his silence, and it is clear that he failed to lift a finger to secure any more cash at all for Scotland in this disgraceful DUP —Tory deal.

‘’As a Tory Secretary of State for Scotland he has completely failed to make the case for Scotland.

‘’He used a series of excuses in an attempt to rewrite the history of what he himself has said about the deal. It simply adds to the sense that he is a lame duck Secretary of State in an increasingly lame duck UK government .

“There is absolutely no way that David Mundell can credibly claim to be standing up for Scotland’s interests in the Cabinet — and his failure to secure anything for the people of Scotland — must now mean his position is utterly untenable. The question now is who will last longer — May or Mundell.’’