THE UK Government is behaving like a “dictatorship” on constitutional matters, Michael Russell has claimed, as he called for equality in relations between the four parts of the United Kingdom post-Brexit.

Giving evidence to the Commons Scottish Affairs Committee on intergovernmental relations, the SNP Government’s Constitutional Relations Secretary told MPs Nicola Sturgeon was once told she "simply wasn't bright enough to understand how good [Theresa May's Brexit] deal was" in a meeting with the Prime Minister.

Mr Russell, who described ministerial relations between London and Edinburgh as “poor,” recalled one meeting he had attended between the First Minister and Mrs May, saying: "What we actually heard was an explanation of why we simply weren't bright enough to understand how good her deal was. Obviously, she wasn't either because her deal changed.

“I must be honest about this, the Prime Minister is not a person who seems willing to listen to what the devolved administrations want to say, still less to compromise as a result of that."

The Scottish minister explained how the “weight of Brexit” was too heavy to bear for the current intergovernmental architecture, which needed to change.

He said: “The change needs to be focused on a relationship of equality if we are to function properly,” pointing out that, after Mrs May’s dash to Strasbourg on Monday for Brexit talks, Arlene Foster, the DUP leader, was briefed on the meeting with Jean-Claude Juncker, the European Commission President, but the First Minister was not.

He argued that under the devolved settlement there was no hierarchy of governments; each one had a defined role. But he noted: “There is a hierarchy of parliaments and that is because Westminster regards itself as sovereign. That centre cannot hold…It is no longer relevant in these circumstances. I want an equality; that is best achieved by independence.”

Mr Russell said a better system would have to be based on a statutory structure where the component parts respected each other, were able to work together, had equal opportunities and an equal say as well as a dispute resolution. “Given the sovereignty of Parliament runs against that, then something will have to give,” insisted the Argyll and Bute MSP.

He was also questioned about the relevance of the role of Scottish Secretary, saying he did “not see what the purpose is; I don't think the role has any function at all".

The Scottish minister insisted the Scotland Office was "not relevant to what we're doing” and was an “appendage from a past settlement that is no longer necessary".

Mr Russell claimed Brexit had changed everything and that for Scotland it might come down to a final choice between “Brexit Britain and an independent Scotland”.

After the meeting, he attacked the “rude words” of Jeremy Hunt, the Foreign Secretary, who dismissed out of hand the notion of a second independence referendum. “We’re not going to accept that type of dialogue,” insisted the Constitutional Relations Secretary.

But asked, given the PM had set her face so strongly against facilitating another independence poll, what the Scottish Government could do practically and if it was not simply blowing in the wind, Mr Russell replied: “Watch this space. I don’t accept the right of the UK Government to operate as if it is a dictatorship and I won’t accept that.”

Meanwhile, a senior Whitehall source stressed: "The Prime Minister has always treated the First Minister with the utmost respect and to suggest otherwise is categorically untrue."

A UK Government spokesman said: "The Secretary of State for Scotland and his office play a vital role in ensuring Scotland's voice is heard at the heart of Whitehall, and that the UK Government's responsibilities and activities in Scotland are fully understood."