An emergency meeting between the European Union and Britain will be held tomorrow to discuss proposed legislation by UK Prime Minister Boris Johnson that intentionally breaches the EU withdrawal treaty.

Maros Sefcovic, the EU vice president in charge of overseeing implementation of the divorce deal, will travel to London to meet his UK counterpart Michael Gove, according to European Commission spokesperson Eric Mamer.

The UK has published a new bill governing post-Brexit trading arrangements within the UK that, by its own admission, violates its treaty with the European Union.

The United Kingdom Internal Market Bill says that certain provisions are "to have effect notwithstanding inconsistency or incompatibility with international or other domestic law".

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

Mr Sefcovic earlier told reporters that Britain is aware that a lack of respect for its Withdrawal Agreement would have consequences, and said that if negotiations are to continue, the bloc must have trust in London.

"For us this is of course a matter of principle," he said. "The trust to continue our discussion on the implementation ... is a must.

"I made it clear that the withdrawal agreement is not open for renegotiation."

Prime Minister Boris Johnson insisted the bill would preserve jobs and peace in Northern Ireland, but his government conceded it lays down unilateral changes in breach of the Withdrawal Agreement with the EU.

The bill says the Northern Ireland protocol is not codified as a permanent solution.

It says a legal guarantee to provide Northern Ireland businesses with unfettered access to its internal market would be in place by the end of its Brexit transition period at the end of the year.

Mr Johnson defended the government's approach.

Asked why the British public at large should respect any laws now, the prime minister told MPs: "We expect everybody in this country to obey the law."

In a bad-tempered exchange with Scottish nationalist MP Ian Blackford, Mr Johnson insisted the bill was about "protecting jobs, protecting growth, ensuring the fluidity and safety of our UK internal market".

"My job is to uphold the integrity of the UK but also to protect the Northern Ireland peace process and the Good Friday Agreement," he added, calling the new bill a "legal safety net" if the EU makes an "irrational interpretation" of post-Brexit arrangements.

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European Commission president Ursula von der Leyen warned Britain that the proposed legislation would break international law if passed and said she was very concerned by the announcements by the British government.

In Latin, a language often used by Mr Johnson, the former German defence minister insisted that "pacta sunt servanda " or "agreements must be kept" and that this was foundation of good relations.

European Council president Charles Michel tweeted: "The Withdrawal agreement was concluded and ratified by both sides, it has to be applied in full.

"Breaking international law is not acceptable and does not create the confidence we need to build our future relationship."