THE Scottish Tories’ top legal expert at Holyrood has said the UK Government’s latest Brexit bill needs to be “significantly and substantially” changed.

MSP Adam Tomkins, who is professor of law at Glasgow University, said it was “highly likely” the UK Internal Market Bill would be rewritten before it was enacted.

The Bill, which prompted Boris Johnson’s top law officer for Scotland to resign last night, proposes to empower UK ministers to break international law. 

In particular, it would allow them to overrule parts of the Withdrawal Agreement signed by the UK and the EU that deal with Northern Ireland.

Democratic presidential nominee Joe Biden yesterday warned the US would not sign a new trade deal with the UK if the Bill jeopardised the Good Friday peace deal.

On Wednesday, Lord Keen, a former Dean of the Faculty of Advocates, resigned as the Advocate General for Scotland over the Internal Market Bill.

The respected QC said he had tried in vain to find a “respectable argument” for the sections on breaching international law, and warned the Bill would add to the UK Government’s many problems.

Asked about Lord Keen’s resignation, Mr Tomkins, who is convener of Holyrood’s justice committee, said he could not give an opinion as committee convener.

However, speaking in a personal capacity, he said: “Personally, I’m very sad to see him go. 

"I think he’s ben an outstanding Advocate General.”

Asked whether he agreed with Lord Keen that the Bill was irreconcilable with his duty to uphold the law as Advocate General, he said: “I think that it’s highly likely that the Bill is going to have to be significantly and substantially amended before it is enacted.”

Mr Tomkins was previously his party’s spokesman on the constitution and strategy.

He has announced he will leave Holyrood at May’s election after one term as an MSP.

The Internal Market Bill is designed to harmonise and prevent barriers within the UK internal market after Brexit and make it easier to strike trade deals with other countries.

The UK Government says the repatriation of powers from Brussels involved will be the biggest gain for Holyrood since devolution.

However the SNP and other parties at Holyrood have described it as a power grab which would trample on Holyrood’s decision-making, and impose English standards on foods and goods in the rest of the UK, regardless of the views of the devolved administrations.