MP Robert Buckland is under pressure to resign as Justice Secretary following the introduction of a controversial bill ministers admit will breach international law.

One critic was former solicitor general Lord Garnier QC, a member of the Conservative Government between 2010 and 2012.

He was asked by Nick Robinson on Radio 4: “Why haven’t the justice secretary and attorney general resigned in protest at the government’s plans to break international law and rewrite the Brexit deal in the event of no deal being reached on future trade arrangements?”

He said: “I can’t speak for them, they must make up their own minds, but I certainly would not be part of a the government and would not want to be a law officer in a government that introduced this legislation.

“The job... is to maintain the rule of law in government and to ensure ministers behave by it. If they insist on not doing so, one’s advice would conflict with the client’s instructions and you would have to go.

“The law officers need to ask themselves some deep questions. This bill when it becomes an act, will be in breach of an international treaty that this government agreed to. If we cannot be trusted to abide by our word on this matter, why would anyone else trust us in future?”

And Mr Buckland is under fire from other lawyers. Prof Mark Elliott, chairman of the law faculty at Cambridge tweeted: “I see Attorney-General @SuellaBraverman & Lord Chancellor @RobertBuckland still haven’t resigned from a Government intent on undermining the rule of law.”

The legal commentator and author who goes under the name of the Secret Barrister tweeted that they did not see how he could remain in post.

“This (as far as I can recall) is unprecedented - a government publicly declaring that it has no intention of being bound by the law,” they wrote.

Asked to respond to Lord Garnier’s comments Mr Buckland’s spokesman said: “He’s entitled to his opinion.”

Mr Buckland himself did not respond when approached directly by the Adver.

The UK Internal Market Bill, introduced this week, is controversial because it could rewrite parts of the Brexit withdrawal agreement and the potential future impact on talks with the EU and the negotiation of international treaties.

Northern Ireland Secretary Brandon Lewis admitted in the Commins on Tuesday that it would break international law in a “specific and limited way.”