NORTHERN Ireland Secretary Brandon Lewis “answered the wrong question” when he said a move to override key parts of the Brexit divorce deal would break international law, according the Tory Advocate General for Scotland.

The UK Internal Market Bill – which gives ministers the power to overwrite provisions in the Withdrawal Agreement relating to Northern Ireland – does not “constitute a breach of international law or of the rule of law”, Richard Keen told peers.

However, the Tory frontbencher’s claim led to cries of derision from the opposition benches in the House of Lords.

In unusually strong language for the upper chamber, he was accused of having talked “a load of rubbish” in arguing that it did not constitute a breach.

The spat came after Lewis sparked a backlash in admitting steps being taken by the Government in relation to the Withdrawal Agreement would break international law in a “specific and limited way”.

READ MORE: Brandon Lewis admits Boris Johnson's Brexit plan will break international law

Tackling the Government at Westminster, Tory peer Lord Lexden said: “Is it not difficult to retain confidence in the Lord Chancellor and the law officers of the Crown when they acquiesce in the Government’s declaration of a willingness to break international law.

“Are they not charged, these officers of the Crown, with responsibility for ensuring that ministers respect the rule of law – national and international – in all circumstances?

“A duty with which permitting threats to break it are hardly compatible.”

But Lord Keen said: “In my opinion, the present Bill does not of itself constitute a breach of international law or of the rule of law.”

Labour’s shadow attorney general Lord Falconer of Thoroton said: “The key characteristic for law officers is not brains – they can get all the advice they want from the English bar of lawyers – it is backbone.”

The Northern Ireland Secretary had confirmed the legislation going through Parliament was a breach of international law, while Lord Keen had “produced a load of rubbish” to peers to claim it was not, said the opposition frontbencher.

Lord Falconer said: “The party that changes its story on law as this Government does shows it lacks backbone.

“How does the Advocate General feel able consistent with personal honour and professional duty to remain as the Advocate General?”

However, responding Lord Keen said: “I have satisfied myself as to the correct legal position in this context.

“It is my view that the Secretary of State for Northern Ireland essentially answered the wrong question.”

His words sparked groans of dissent and Lord Falconer could be heard to cry in exasperation: “For goodness sake – he is a Cabinet minister.”

Lord Keen responded: “I hope he has not become unwell in view of the noises emanating from him. But if he has, I wish him well for the future.”

He added: “We are in a situation in which we have rights under an international treaty. Those rights include our response to any breach of obligations by the counter-party, be that a lack of good faith or such action as would fundamentally alter the obligations under the treaty giving rise to a position… where we could withhold our operation of the treaty.”

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Tory former solicitor general Lord Garnier said: “The Bill that we are considering disapplies sections of a treaty which we have freely entered into.”

He questioned “how does that fit” with the first duty of the law officer being to uphold the rule of law.

Lord Keen said: “As regards the present Bill, it is designed to provide for a contingency which will only operate in the event of us having to respond to a material breach or a fundamental change in obligations and then only by bringing forward regulations that will require the approval of this House.

“Unless and until that occurs, there is no breach of the treaty. There is simply a means by which the treaty obligations can be addressed in the event of a breach.”

It comes as Lord Keen was told to prove he is a man “of integrity and honour” and resign from Boris Johnson's “law-breaking administration”.

READ MORE: More pressure on Richard Keen to quit over illegal Internal Market Bill

In a savage editorial, Scottish Legal News, urges Lord Keen to disassociate himself from “the charlatans at No 10 Downing Street”.

The highly respected magazine, which is sent to just about every lawyer and solicitor in Scotland, says that failure to do so would “endorse reckless and lawless behaviour that will tarnish Britain’s reputation and ultimately that of those associated with it.”