THE Scottish Parliament risks being undermined by a Downing Street 'power grab' as Europe relinquishes control over key laws returning to the UK, the influential Brexit committee at Westminster has warned.

The status of the devolved administrations would be under threat if ministers decide to make many more decisions in London amid calls to protect Holyrood’s range of powers, according to the Commons Exiting the EU Committee.

Former Scottish Secretary Alistair Carmichael, the only Liberal Democrat on the committee, called the report a “devastating critique of the shambles that is the Conservative Brexit strategy” while others said its conclusions has been “unduly negative”.

It was published weeks after Nicola Sturgeon accused Theresa May’s government of a “grabbing power” from Scotland.

The First Minister said that control of devolved areas, such as agriculture, should transfer from Brussels to Holyrood after the UK leaves the European Union (EU).

But the Conservative Government’s White Paper on Brexit says that some powers – such as the regulation of the fishing industry – may pass to Westminster instead.

Tory ministers deny charges they are attempting to hoard powers and say they need to protect the integrity of the UK’s single market.

But the controversial report warns: “There is a real issue… of the protection of the position of the devolved nations in relation to decisions taken in London.”

MPs insist that this will require “at the very least, a much more thoroughgoing system of intergovernmental relations, extending possibly so far as shared decision-making”.

The report also calls on Tory ministers to take account of Scottish Government priorities during EU negotiations, provide an “urgent” response to proposals for an alternative deal for Scotland and consider the call for a separate immigration system.

UK ministers have consistently rejected the prospect of different schemes on either side of the border.

MPs also say legislation implementing Brexit is likely to require the consent of Holyrood and stresses that sufficient time must be allocated to allow MSPs to scrutinise the final deal with Brussels.

The highly critical report also describes as “unsubstantiated” Mrs May’s claim that no post-Brexit trade deal with Europe would be better than a bad deal.

The committee says ministers should calculate the cost of crashing out of the EU without agreement and offer MPs a vote to reject Brexit under those circumstances.

The report split the 20-strong committee, which has 10 Tory members, with six pro-Brexit MPs voting against its publication amid reports of a walkout by members who denounced the document as being "too gloomy".

Five Conservatives – including former ministers John Whittingdale and Dominic Raab – and the Democratic Unionist Party MP Sammy Wilson voted to withhold publication of the report.

But they were outnumbered by a collection of 10 Labour, Tory, Liberal Democrat, SNP and SDLP MPs.

Nicola McEwan, professor of politics at Edinburgh University, told the MPs that the UK Government’s explanation of repatriation of competences was “ambiguous” and “an obvious source of tension as the negotiations get under way”.

Committee member Peter Grant, an SNP MP, said: “The report recognises the lack of engagement and respect by the UK government towards devolved administrations and on the compromise paper put forward by the Scottish Government which has fallen on deaf ears.”

But former Culture Minister John Whittingdale branded its conclusions “unduly negative”.

Mr Raab added: “The report was rushed, skewed and partisan. After two reports that had strong support, it’s regrettable that this one split the committee. That undermines its credibility and influence, but I hope and expect the committee will learn the right lessons as we move forward.”

Last night, Brexit secretary David Davis said: "We are clear that no deal is not what we want or expect, but that it would be better than a deal which sought to punish the UK.

"A responsible government should prepare for all potential outcomes, including the unlikely scenario in which no mutually satisfactory agreement can be reached, and that is exactly what we are doing.

"We have also been analysing the impact of different scenarios on different sectors of the economy.

"We are clear that no deal is not what we want or expect, but that it would be better than a deal which sought to punish the UK."

He added: "As the Prime Minister has said, the Government is committed to creating a global Britain that will be stronger, fairer, more united and outward-looking than ever before.”