On Wednesday, the European Commission filed a new legal action against Britain, accusing it of endangering Northern Ireland's peace by attempting to renegotiate the post-Brexit trade deal.

"The UK government tabled legislation confirming its intention to unilaterally break international law," EU commission vice-president Maros Sefcovic said. 

"More precisely to break an agreement that protects peace and stability in Northern Ireland," he said.  "Opening the door to unilaterally changing an international agreement is a breach of international law, as well. So let's call a spade a spade. This is illegal." 

The British government introduced legislation on Monday to repeal post-Brexit trading rules for Northern Ireland, in an attempt to circumvent the EU withdrawal treaty that it had signed.

Prime Minister Boris Johnson's government stresses it is not breaking international law, citing a "necessity" to act to restore Northern Ireland's power-sharing institutions. 

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However, Brussels rejects this argument, and Sefcovic stated that legal action would be taken, with two new cases joining those suspended by the commission. Sefcovic stated that the EU would reopen a case filed last year to control the export of certain food products from the United Kingdom to Northern Ireland.

"If the UK doesn't reply within two months, we may take them to the Court of Justice," he warned.  "Second, we are launching two new infringements against the UK," he said, announcing cases that could see the British government brought before the European Court of Justice. 

"One for failing to carry out the necessary controls at the border control posts in Northern Ireland by ensuring adequate staffing and infrastructure. And one for failing to provide the EU with essential trade statistics data to enable the EU to protect its single market."

EU threatens legal action over UK's Northern Ireland trade bill

Two days ago, the European Union threatened legal action against the United Kingdom after the latter's government proposed legislation that suggests a unilateral overhaul to the post-Brexit trade deal it signed for Northern Ireland.      

European Commission Vice President Maros Sefcovic stated to reporters in Brussels that "It is with significant concern that we take note of today's decision by the UK Government to table legislation," adding that "Unilateral action is damaging to mutual trust. The Commission will now assess the UK draft legislation." Sefcovic handles the EU's fraught ties with the UK government.

The Europeans would not renegotiate the divorce deal and its special protocol for trade in Northern Ireland, he said, and this "will simply bring further legal uncertainty for the people and businesses in Northern Ireland."