THE UK Government is behaving like “Big Brother” and needs to shift further on the Brexit devolution powers or face a constitutional crisis of its own making, the SNP’s Ian Blackford has insisted.

The Nationalist leader at Westminster accused Theresa May and her colleagues of “behaving abominably” in their relations with Edinburgh and made clear the Scottish Government was not prepared to budge on what it regarded as a matter of principle.

During a rowdy PMQs, the Highland MP said it was “no surprise” the Scottish and Welsh Governments were putting forward Continuity Bills to stop the Westminster “power-grab”.

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But the Prime Minister, noting how her administration had given an "absolute commitment" to amending the EU Withdrawal Bill, insisted there was no need for the Scottish and Welsh bills that were being introduced.

"The proposals being put forward are unnecessary," declared Mrs May, stressing the focus should be on reaching a deal over clause 11; the section of the Withdrawal Bill that deals with devolved powers.

"We are committed to protecting and enhancing our British Union of England, Scotland, Wales and Northern Ireland. The devolved administrations should be fully engaged in preparations for the UK's exit.

"It's our intention that the vast majority of the powers returning from Brussels will start off in Edinburgh, Cardiff and Belfast, not in Whitehall. We will continue to talk to the devolved administrations because we also need to ensure that we maintain the single market of the United Kingdom," she explained.

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Downing Street later repeated the UK Government had made a “substantial offer” ie that most powers would go directly to Holyrood. Stressing the bill was a vital piece of legislation, a spokesman said: “Those discussions are going to continue between ministers in Westminster and ministers at Holyrood and elsewhere.”

One senior source remained hopeful that as more talks took place a deal could be done to avert a constitutional crisis. “Both sides want a deal; you have to be optimistic,” he said.

An intergovernmental Joint Ministerial Committee took place last week and one is now pencilled in for next Thursday with a face-to-face meeting between Mrs May and Nicola Sturgeon expected before March 22, the last date the UK Government can table an amendment to its Brexit legislation and the day when the key EU Council meets in Brussels to try to agree a deal on the transition period.

Following PMQs, Mr Blackford claimed there had been “very little desire” on the part of Whitehall to get to a position of agreement with Edinburgh but there was still time to seal a deal.

“If you are to respect the principle of devolution and specifically what was in the 1998 Scotland Act, which defines very simply what is devolved and what is reserved, you can’t have a situation where you say you are respecting the devolved institutions but you are retaining a veto in 25 areas of significant importance on agriculture, fisheries and the environment,” argued the SNP leader.

“The UK Government is going to have to change its position. I would say respectfully to it: you are playing with that devolved settlement; this is not about the SNP but about what you are doing to the powers of the Scottish Parliament.”

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The MP for Ross, Skye and Lochaber claimed there was “no single market in the UK” like there was across Europe, which had been arrived at through treaties.

“You are talking about the fact we are part of a unitary state, so you don’t have the kind of agreements the PM is talking about.”

He added: “We can’t have Westminster simply acting as Big Brother and holding that power of veto over the parliaments in Edinburgh and Cardiff; it’s not acceptable. In those circumstances, we could not be in a position to pass a Legislative Consent Motion. But we want to be in a position to do so but we can’t have powers being taken back from the people of Scotland and the parliament of Scotland.”