The European Commission launched two new legal proceedings against Britain on Wednesday after London published plans to override some post-Brexit rules governing Northern Irish trade, and resumed another challenge it had previously paused.
The proceedings could result in the European Court of Justice (ECJ) imposing fines, although these would likely be more than a year away.
London has proposed scrapping some checks on goods from the rest of the United Kingdom arriving in the British province and challenged the role of the ECJ to decide on parts of the post-Brexit arrangement agreed by the EU and Britain.
European Commission Vice President Maros Sefcovic, who oversees EU relations with former EU member Britain, said there was no justification for unilaterally changing an international agreement
"Let's call a spade a spade. This is illegal," he told a news conference, adding it cast a shadow on relations at a time when international cooperation was even more important, a reference to the alliance against Russia's invasion of Ukraine.
A spokesperson for British Prime Minister Boris Johnson said London was disappointed by the EU's legal moves.
"The EU's proposed approach, which doesn't differ from what they've said previously, would increase burdens on businesses and citizens and take us backwards from where we are currently," he said, referring to EU proposals to ease post-Brexit trade problems with Northern Ireland.
The three legal proceedings do not relate to Britain's new plans, but to the EU belief that Britain has failed to implement the protocol that governs Northern Irish trading.
The two new suits charge Britain with failing to ensure adequate staff and infrastructure to carry out checks in Northern Ireland and not providing the EU with sufficient trade data.
The other, paused a year ago to improve the atmosphere around talks, relates to the movement of agri-food products. Sefcovic said the EU might take the case to the ECJ if Britain failed to address the EU's charges within two months.
Sefcovic said Brussels still wanted to resume talks with Britain to resolve difficulties in shipping British products to Northern Ireland.
"We decided that our response should be measured, should be proportionate. And we are offering not only legal action here today but we've been fleshing out what concretely we could do," he said.
The British province is in the EU single market for goods, meaning imports from the rest of the United Kingdom are subject to customs declarations and sometimes require checks on their arrival. The arrangement was set to avoid reinstating border controls between Northern Ireland and EU member Ireland, which were dropped after the 1998 Good Friday peace agreement.
The arrangement has inflamed pro-British unionist parties by effectively creating a border in the Irish Sea.
The Commission made a series of proposals last October to ease customs formalities and cut checks.
(Reporting by Philip Blenkinsop and John ChalmersAdditional reporting by Liz Piper in LondonEditing by Mark Potter)
