Britain plunged Brexit trade talks into crisis on Wednesday by explicitly acknowledging it could break international law by ignoring some parts of its European Union divorce treaty, prompting a rapid rebuke from the EU’s chief executive.

Brushing aside warnings from Brussels that breaching the treaty would prevent any trade deal being struck, London said in the proposed legislation that it would ignore parts of the Withdrawal Agreement, which was only signed in January.

The Internal Market Bill spells out that certain provisions are “to have effect notwithstanding inconsistency or incompatibility with international or other domestic law”.

The government has said international law would be broken “in a very specific and limited way”.

Ursula von der Leyen, president of the European Commission, promptly tweeted that she was “very concerned” about the British government’s intentions.

“This would break international law and undermines trust. Pacta sunt servanda = the foundation of prosperous future relations,” she said. The Latin phrase, meaning “agreements must be kept”, is a basic principle of international law.

John Major, a former Conservative prime minister, warned the government that “if we lose our reputation for honouring the promises we make, we will have lost something beyond price that may never be regained”.

The bill’s publication, on the day the EU’s chief negotiator arrived in London for a new round of trade talks, suggested to some that Prime Minister Boris Johnson might be trying to goad the bloc into storming out of those negotiations.

But EU sources told Reuters they would not seek a suspension. Although EU officials expressed dismay, one said that giving up on the negotiations “would only play into the U.K. game”.

Johnson told parliament the bill was “a legal safety net to protect our country against extreme or irrational interpretations” of the Withdrawal Agreement’s Northern Ireland protocol that could threaten peace in the British province.

The bill, if approved, would give ministers the power to ignore parts of that protocol by modifying the form of export declarations and other exit procedures.

But the list of specific agreements that might be ignored includes not only provisions of the Northern Ireland Protocol but also “any other provision of the EU Withdrawal Agreement” and “any other EU law or international law”.

The bill says Britain may ‘disapply’ provisions including one that relates to Northern Ireland and state aid. Johnson’s team see state aid as crucial for ensuring they can incubate new global technology firms and help “level up” parts of Britain.

Johnson’s spokesman said the EU divorce deal was like no other treaty and had been “agreed at pace in the most challenging possible political circumstances”. Opponents accused him of blatant hypocrisy after promising before December’s election that he had an “oven-ready deal”.

The bill will be debated in both chambers of parliament and require their approval before becoming law.

Britain quit the EU in January but has remained part of its single market, largely free of trade barriers, under a status quo agreement that expires in December. It has been negotiating a trade deal to take effect from Jan. 1, but says it is willing to walk away if it cannot agree favourable terms.

The agreement calls for border-free trade on the island of Ireland, which the EU says should in some cases require checks on goods passing between Northern Ireland and mainland Britain. But Johnson has ruled out requiring export declarations or tariffs on such goods.

Some fear that a failure to agree on border arrangements could jeopardise the 1998 Good Friday Agreement which largely ended three decades of political and sectarian conflict in Northern Ireland.

Irish Prime Minister Micheal Martin said he would speak to Johnson to express “very strong concerns” about the plans while his deputy Leo Varadkar called it a “kamikaze” threat that had backfired.

Senior members of Johnson’s Conservative Party have already voiced anger that Britain might consider breaking international law, and the bill, Scotland and Wales say, will weaken the fabric of the United Kingdom itself by stealing powers from them and Northern Ireland.

Asked how he could expect Britons to obey the law if his government was willing to undermine it, Johnson said: “We expect everybody in this country to obey the law.”

Reuters