BRUSSELS — The European Union announced on Monday that it is taking legal action against Britain for what it called a violation of a legal agreement over Brexit and Northern Ireland that was part of a trade pact forged between the two sides last year.
European officials said Brussels was responding to a move this month by the British government to unilaterally ease trading and border rules for Northern Irish businesses by extending a grace period for implementation of the Brexit accord.
Under a protocol on Northern Ireland that was part of the pact, Britain is required to consult the European Union on changes to its implementation — which it did not do. The protocol was aimed at ensuring that there was no hard border between Ireland, a member of the bloc, and Northern Ireland, which is part of the United Kingdom.
The officials said Britain had twice in the last six months unilaterally broken the agreement, first with a bill last December that dropped some elements objected to by the European Union, and then with the unilateral decision earlier this month to extend a grace period for British goods arriving in Northern Ireland until Oct. 1.
The Northern Ireland protocol draws a border between Britain and the European Union in the Irish Sea, effectively keeping Northern Ireland within the European single market for goods. Britain has left the single market, so keeping goods flowing smoothly from the mainland to Northern Ireland, despite new legal checks for sanitary and health regulations and considerable paperwork, has been a significant problem.
That is why both sides agreed to a grace period on numerous border requirements, to run until the end of March, to adjust to the deal, which went into effect on Jan. 1.
But trade disruptions for Northern Ireland have been so severe that Britain decided to extend the grace period for food and parcels and horticultural products — and include other issues, like pets, which had not been agreed upon — for six months, until October.
The British government has denied breaching the agreement, arguing that the unilateral extension of grace periods was common under trade agreements, a position rejected by European officials.
Speaking in Coventry on Monday, Prime Minister Boris Johnson said the British actions were “temporary and technical measures that we think are very sensible.” He said that Britain looked forward “to our discussions with our E.U. friends and see where we get to.”
A Downing Street spokesperson said on Monday that the measures were “temporary to avoid disruption in Northern Ireland.”
Britain remains committed to the Northern Ireland protocol, the spokesperson said, and wished to address issues that had arisen at the border with Brussels through the proper channels.
But so far, a European Union official said, that stated British desire has not been reflected in fact or action. Britain’s actions had undermined trust in its word, the official said, arguing that the only way forward was to try to reestablish trust and the commitment of both sides to the deal they negotiated. Britain has also violated the “duty of good faith” requirement in Article Five of the withdrawal agreement that governed Brexit, the official said.
The European officials said that despite the initiation of legal action, they hoped that further discussions between Brussels and London would resolve the problems before the issue came before any court.
Maros Sefcovic, the bloc’s top Brexit official, has written to David Frost, his British counterpart, urging Britain to refrain from putting the unilateral steps into practice and instead work with Brussels to find joint solutions that could provide British businesses stability and predictability.
“The E.U. and the U.K. agreed the protocol together,” Mr. Sefcovic wrote. “We are also bound to implement it together. Unilateral decisions and international law violations by the U.K. defeat its very purpose and undermine trust between us.”
Relations between Britain and the European Union have been tendentious for some time over issues surrounding the Northern Ireland protocol, the larger agreement on Britain’s withdrawal from the bloc, and over vaccine supplies.
Brussels has accused Britain of holding back vaccines scheduled for Europe and even of a ban, which does not exist, on vaccine exports. In return, the British government has touted the speed and success of its vaccine procurement and rollout, comparing it to the slower pace of the European Union, and argued that Brexit has made that success possible.
The legal process over the grace period allows Britain a month to respond, and another month for examination. If not resolved before then, Britain could be brought before the European Court of Justice and face trade sanctions.