Brussels - The European Commission launched new legal action against Britain on Wednesday, accusing London of putting peace in Northern Ireland at risk by trying to overhaul 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."

On Monday, the British government introduced legislation to rip up post-Brexit trading rules for Northern Ireland, in an attempt to override the EU withdrawal treaty that it had signed.

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

But Brussels rejects this argument, and Sefcovic said that legal action would be taken, with two new cases joining those the commission had suspended. Sefcovic said the EU would revive a case is launched last year to control the export of certain food products from Great Britain 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.