THE SNP’s alternative Brexit Bill has passed its first hurdle at Holyrood, taking the Scottish and UK governments closer to a constitutional crisis.

MSPs agreed the general principles of the EU (Legal Continuity) (Scotland) Bill by 94 votes to 30, with only the Conservatives refusing to support the “backstop” legislation.

However other parties criticised the detail of the Bill, and demanded there be amendments in the coming fortnight.

A key complaint was that ministers are proposing to give themselves - not parliament - the power to shadow EU law for up to 15 years after Brexit.

The continuity Bill is scheduled to pass by March 21 if the Scottish and UK government cannot reach a deal on the distribution of devolved powers after Brexit.

The two sides are deadlocked over where 25 of the 111 devolved areas due to be repatriated from Brussels should lie, with the UK saying they need to be at Westminster pending the creation of pan-UK frameworks needed to harmonise the internal market.

The Scottish Government says any such frameworks must be agreed through consent, not imposed.

Although talks continue, progress has stalled, as whichever parliament ends up with the powers would have a de facto veto over the other, so neither side wants to concede.

Holyrood’s presiding officer, Ken Macintosh, has said the SNP Bill is not legislatively competent as it breaches EU law, while the Scottish Government’s most senior law officer, the Lord Advocate James Wolffe QC, has said it is competent.

If the Bill is passed, the UK Supreme Court is expected to be asked to rule on its legality.

SNP Brexit minister Michael Russell told MSPs a “crucial issue of principle” still divided the two governments, but he was “hopeful” of reaching an agreement.

However, the Bill was needed as a contingency measure.

He said: “I believe we should stand up for the rights of this Parliament because that's standing up for the rights of the people of Scotland.

“I'm confident the bill will receive extensive scrutiny in the time available - the government will and should find that a challenging process, and we will face up to it.”

Tory MSP Adam Tomkins called the Bill “wrecking legislation” that undermined devolution, and was designed to derail talks with London as part of a wider SNP political gambit.

He said: “This Bill is unnecessary, seriously flawed, ill-thought through and incoherent.

“It’s not a bill for continuity – it’s a wrecking bill to cause constitutional confusion and chaos.”

He claimed that, by admitting the Bill was not normal, the SNP Government had disapplied the Sewel Convention, which says Westminster will not “normally” legislate in devolved areas without Holyrood’s consent.

He said: “The UK Parliament is now free to legislate on EU withdrawal even if we do not give our consent to the [Westminster] EU Withdrawal Bill.

"Far from safeguarding the interests of this parliament, this bill and the way it is to be enacted in haste have completely undercut and betrayed the interests of this parliament."

Labour's Neil Findlay gave the Bill "cautious support", but warned there would be “no blank cheque” on the fine detail.

He said: "We have very serious concerns about timetabling, about the rushed nature of the bill, about the limited time for consultation, the rights of people we represent to shape its content, and the powers it seeks to place in the hands of ministers."

He said ministers had kept MSPs "in the dark" about the details of the row with the UK.

"It is unacceptable that we cannot see what is causing this stand-off," he said.

Green MSP Patrick Harvie backed the Bill, and said the UK had failed to amend its own Brexit legislation too many times to be trusted, and a deal was “vanishingly unlikely”.

LibDem Tavish Scott said the Bill was “necessary but flawed”, and gave too much power to ministers in its current form, and so would need to be amended.

Earlier, Mr Russell rejected a call from the Law Society of Scotland for ministers and the Presiding Officer to publish their full legal advice on the Bill’s competence.

The Society’s director, Michael Clancy, said that although such advice was usually secret, it was possible to publish it, and the country was facing “extraordinary circumstances”.

Mr Russell said that would take the government into “completely uncharted waters” and set a “very difficult and dangerous precedent”.

The Lord Advocate has already given an exceptional statement to MSPs setting out why the government believed the Bill to be within Holyrood’s powers, he added.

Scottish Tory leader Ruth Davidson said the SNP “actively wants a row” over the Brexit legislation to push its contention that Westminster has mounted a “power grab”.

She said “It’s the SNP, not Westminster, who are failing to respect the devolution settlement in fast-tracking unconstitutional legislation through Holyrood with minimum scrutiny.”