A NEW constitutional crisis is looming as the Scottish Government threatens to reject the Brexit Bill even if Westminster bows to its demands for more powers.

Michael Russell, Scotland’s Brexit Minister, said there are other elements of the Bill that the SNP “thoroughly dislike” beyond the proposal to transfer all the EU’s current powers to London rather than hand them to the devolved nations.

The SNP will table a series of amendments in the Commons today to try to prevent “the biggest power grab Scotland’s Parliament has faced since being reconvened in 1999”.

Mr Russell said the devolution amendments are “non-negotiable” if the UK Government wants the SNP to recommend support for the Bill in the Scottish Parliament.

However, he suggested the Scottish Government could still refuse to table a legislative consent motion (LCM) – whereby Holyrood gives consent to Westminster legislating on normally devolved issues – even if the “power grab” is loosened.

“There are things in the Bill that many people, including ourselves, thoroughly dislike,” he said.

“The Bill has a lot of things that are really problematic, not least the issue of human rights, which has not be address, the issue of protections for the environment hasn’t been addressed, the issue of the Charter of Rights hasn’t been addressed.”

He added: “If we refuse (a LCM) then the constitutional crisis deepens and the House of Lords will look very askance at the Bill.

“Secondly, as a practical business, the UK is leaving the EU, and many of us think that is a daft idea, so can we get frameworks in place that will allow us to continue to operate, for example in agriculture, environment, and certain legal areas without a cliff edge? It’s about that cliff edge.”

Mr Russell said the Scottish Government is working to overcome the obstacles to an LCM but insisted “there has to be changes to the Bill”.

“That is non-negotiable. Now what these changes are and how they operate are still under discussion,” he said.

His intervention comes at the start of a crucial week for Mrs May which could determine whether EU leaders give the go-ahead for the second phase of the Brexit negotiations – including trade talks – to begin.

The Prime Minister travels to Brussels today to meet European Commissioner Jean-Claude Juncker with the EU side insisting she must improve her offer on the terms of Britain's withdrawal if there is to be progress at the EU's December summit.

She is also facing continued pressure from Scotland, with Labour calling on the 13 Scottish Tory MPs to "make good on their rhetoric and stop this Westminster power grab".

Mr Russell also put pressure on the Scottish Conservatives to support the SNP’s amendments, after senior Tories suggested they could back some of the SNP’s proposals or bring forward their own amendments.

However, he said the Tories’ warm words have yet to be translated into action.

“There are no such amendments and you would have to ask the Scottish Conservatives why they haven’t brought those forward,” he said.

“If there are alternative amendments that achieve the same thing and those are brought forward by anybody, we will of course sit down and discuss them, but we have to see them. Talking about them isn’t enough.”

He added: “I don’t want to leave anybody in any doubt, if the Bill cannot be amended there cannot be a legislative consent motion, there cannot be the progress that the government wants.”

Scottish Secretary David Mundell said the UK Government is very close to reaching an agreement with Holyrood, but admitted “the SNP might vote against the Bill”.

“What we are engaged in, in the discussions with the Scottish Government, is about getting the devolution aspects of the Bill right,” he said.

“We’ve put in a great deal of work on both sides over the last few months and I think that we are very close to getting agreement on exactly what should happen to each of the 111 issues on the list that was published, how they should be dealt with after we leave the EU where some of those powers and responsibilities will come directly to the Scottish Parliament.

“Some will be dealt with by informal arrangements across the UK and there will be a small number for which legislative mechanisms will be required.

“I think we’re very close to reaching agreement on exactly how that distribution will take place.”

Ian Blackford, the SNP’s Westminster leader, urged Scottish Conservative MPs to reject the “power grab”.

“All powers in devolved areas returning from Brussels must be returned to the Scottish Parliament, he said.

“Anything less would breach the founding principles of devolution and would be a complete betrayal of promises made during the EU referendum.

“The Scottish Tories must join with the SNP today and support our amendment and protect devolution.”