BORIS Johnson has been accused of “running a clear and deliberate anti-devolution policy” by Scotland’s Constitution Secretary.

Mike Russell criticised proposals to establish a new internal market between the four nations at the end of the Brexit transition period, claiming "every devolved power could be undermined".

He argued the proposed legislation considers Westminster to be sovereign in trade and regulation disputes, and the UK Government "have a veto on everything".

Giving evidence to Holyrood's Finance and Constitution Committee, he told MSPs the Scottish Government will continue to challenge the Bill and did not rule out legal action to challenge the plans.

READ MORE: UK Government blows off MSPs 36 minutes before power grab meeting starts

"This is an outrageous power grab and it is a major weakening of devolution, and it should not be permitted to take place," he said.

"My view is that it reveals completely the agenda of the current UK Government, which is hostile to devolution and hostile particularly to Wales and Scotland for exercising their rights under devolution."

Russell suggested policies enacted by devolved governments could be rejected by Westminster.

He added: "It is highly likely that the UK Parliament will apply English votes for English laws so in actual fact Scottish representatives won't even get to vote on issues of standards in the UK Parliament - they will be excluded from that.

"Then the Scottish Parliament will be overridden.

"If that is not contrary to the spirit of devolution, I don't know what is."

Describing relations between the UK and Scottish Governments, Russell said: "Things have got definitely worse in last year with the advent of the Johnson administration, which I think is running a clear and deliberate anti-devolution policy."

UK Business Secretary Alok Sharma rejected an invitation to give evidence to the committee, convener Bruce Crawford said.

The UK Government launched a consultation on the proposals, running from July 16 to August 13. Because it started during the Holyrood recess, it left MSPs with one possible day to take evidence before the consultation ends.

Tory ministers failed to confirm until today, 36 minutes before the meeting, whether or not they would attend the evidence-giving session.

Scottish Greens co-leader Patrick Harvie, who has been extremely critical of the power grab proposals, tweeted this morning: “Today is the only chance MSPs have to take evidence on this UK power grab, before the consultation ends. Now, 36 minutes before the meeting starts, the UK Government finally confirm they are refusing to attend. Their contempt for Scotland knows no limits.”

Previously, Cabinet Office minister Michael Gove insisted a "power surge is occurring" which will see "scores of new powers" transferred to the Scottish Parliament.

Scottish Secretary Alister Jack said the changes will ensure "seamless trade continues across all parts of the UK" when the Brexit transition period ends on December 31.

"Our proposals respect and strengthen devolution," he added.

"I hope the Scottish Government will work with us as we take this forward for the benefit of businesses and consumers in Scotland."