BRITAIN'S relationship with the EU has been plunged into crisis after ministers rejected a demand by Brussels to drop plans to override key elements of the Brexit Withdrawal Agreement.

At a stormy meeting in London, European Commission vice president Maros Sefcovic gave the UK until the end of the month to drop the controversial provisions in the Internal Market Bill or face the potential collapse of talks on a free trade agreement.

However, Cabinet Office Minister Michael Gove - who co-chairs a joint committee on the Withdrawal Agreement with Sefcovic - said the Government was not prepared to back down.

"I explained to vice president Sefcovic that we could not and would not do that," he told reporters following the meeting.

"I made it perfectly clear to vice president Sefcovic that we would not be withdrawing this legislation. He understood that. Of course he regretted it."

READ MORE: How Brexit opened the door to new levels of absurdity

The emergency talks were called after ministers admitted on Tuesday that provisions in the Bill to enable the Government to change elements of the Withdrawal Agreement relating to Northern Ireland were in breach of international law.

In a strongly worded statement following the meeting, the European Commission said Sefcovic had made clear the British proposals had "seriously damaged trust" between the two sides and that it was up to the UK side to repair the relationship.

It said that he had made clear that the EU would "not be shy" in using the "mechanisms and legal remedies" contained in the agreement to address any violations if the UK did not withdraw the provisions.

"Violating the terms of the Withdrawal Agreement would break international law, undermine trust and put at risk the ongoing future relationship negotiations," the statement said.

"The EU does not accept the argument that the aim of the draft Bill is to protect the Good Friday Agreement. In fact, it is of the view that it does the opposite.

"Vice-president Maros Sefcovic called on the UK Government to withdraw these measures from the draft Bill in the shortest time possible and in any case by the end of the month."

Gove denied the Government was seeking to set aside the Withdrawal Agreement or to "shirk" from the protocol on Northern Ireland which means that some goods entering from the rest of the UK will still be subject to EU tariffs.

"We are absolutely serious about the implementation of the protocol," he said "But we have to ensure the protocol is implemented in a way that respects the fact that Northern Ireland is an integral part of the United Kingdom, part of our customs territory, and it is British ministers in Westminster who are responsible for good governance in Northern Ireland."

READ MORE: Why the UK's readiness to break its word on Brexit should worry us all

Gove said he still hoped the two sides could resolve their differences through the joint committee but refused to be drawn on the prospects of their succeeding.

"It is not for me to speculate about the chances for success. It is my job to work for success," he said.

The row erupted as the latest round of talks between the EU and UK chief negotiators, Michel Barnier and Lord Frost, on the post-Brexit relationship, including a free trade agreement, ended with both sides saying "significant differences" remained.

In a statement released earlier today, Barnier said: "The UK is refusing to include indispensable guarantees of fair competition in our future agreement, while requesting free access to our market."

He added: "The UK has moreover not engaged on other major issues, such as credible horizontal dispute settlement mechanisms, essential safeguards for judicial cooperation and law enforcement, fisheries, or level playing field requirements in the areas of transport and energy. 

"To conclude a future partnership, mutual trust and confidence are and will be necessary."

Meanwhile, there was growing unrest among senior Tories at the prospect the UK could go back on an international agreement, with Lord Howard becoming the third former party leader, after Theresa May and Sir John Major, to criticise the plan.

Speaking in the House of Lords, he accused the ministers of damaging the UK's "reputation for probity and respect for the rule of the law".

READ MORE: New poll reveals half of Tories are okay with No-Deal Brexit - but noone else is

"How can we reproach Russia or China or Iran when their conduct falls below internationally accepted standards, when we are showing such scant regard for our treaty obligations?" he said.

Another Tory grandee, former chancellor Lord Lamont, warned the legislation would not get through the upper House unless there were changes.

"The Government are in a terrible mess and in a hole and I don't think it is easy to justify.

"In a way, this could take us back to square one with a terrible dilemma," he told BBC Radio 4's PM programme.