The White House has urged London and Brussels to work together to preserve the peace in Northern Ireland, after the EU formally launched legal action against the UK over Brexit arrangements in the region. Joe Biden’s spokesperson said: “We continue to encourage both the EU and the UK government to prioritise pragmatic solutions to safeguard and advance the hard-won peace in Northern Ireland.” The remarks comes ahead of a virtual summit tomorrow between Biden and the taoiseach, Micheál Martin, to mark St Patrick’s Day, a key date in the American-Irish political calendar. Earlier Martin warned at a Washington online event that the UK’s decision to unilaterally delay implementation of parts of the Northern Ireland protocol corroded trust and exacerbated uncertainty and instability, “two things Northern Ireland can well do without”. The EU’s legal action on Monday is the second time in six months that Brussels has launched infringement proceedings against the UK over Brexit, following last year’s threat by the British prime minister to override part of the withdrawal agreement through the internal market bill. Ultimately the action could see a case held at the European court of justice and lead to financial penalties and trade sanctions. The EU has accused the UK of breaching the good faith provisions in the withdrawal agreement after its unilateral decision two weeks ago to delay implementation of part of the Northern Ireland protocol relating to checks on goods shipped from Great Britain to the region. The formal notice of legal action was issued with an accompanying letter from the European commission vice-president, Maroš Šefčovič, to the new Brexit minister David Frost. It calls on the UK to “rectify and refrain from putting into practice” its decision on 3 March to extend grace periods for checks on supermarket goods crossing the Irish Sea. An EU official said: “The UK must stop acting unilaterally and stop violating the rules it has signed up to.” The UK has been given one month to submit its observations under the formal notice. If it fails to enter into consultations in good faith the EU can launch a dispute settlement mechanism which, if not solved, could “ultimately result in the imposition of financial sanctions” or a suspension of the withdrawal agreement in all aspects bar the agreement on EU citizens. Šefčovič said “unilateral decisions and international law violations by the UK defeat its very purpose and undermine trust between us”. The letter alleges “breaches of substantive provisions of EU law concerning the movement of goods and pet travel made applicable by virtue of the protocol on Ireland and Northern Ireland”. It invokes article 12, clause 4, of the Northern Ireland protocol as well as the wider provisions on movement of goods under article 258 of the Treaty on the Functioning of the European Union. The EU also accuses the UK of breaching the duty of good faith under article 5 of the withdrawal agreement. The bloc hopes its two-pronged legal and political approach will act as carrot and stick to resolve the Northern Ireland protocol row over checks on supermarket goods, plants and parcels introduced in Northern Ireland on 1 January. EU sources say they hope the legal action will “register our discontent” over the unilateral decision but hope that the matter can be resolved through further negotiations on the Northern Ireland protocol. “The EU is responding to a violation of international law through the rules provided in the agreement. “We hope that the legal route will not become necessary. This is an issue which we hope we will find an amicable joint solution” “What we need in order to implement the protocol is mutual trust and this kind of unilateral action that we see from the UK, does not build trust,” said the EU official. A UK government spokesperson said the moves to extend the grace period unilaterally was “lawful and part of a good faith implementation” of the protocol, adding they were “temporary, operational steps” to minimise disruption to ordinary lives. In what appeared to be a move to calm heightened tensions, it said it looked forward to “discussing the issues within the joint committee framework in a constructive fashion”. The statement noted the protocol was only in place for 70 days and had created challenges for supermarkets and others and the “low-key move” did not warrant legal action. In a nod to the campaign mounted by the DUP to scrap the protocol, the government said “all sides need to keep in mind that the protocol depends on cross-community consent and confidence” to work. EU sources said while they hope to “find an amicable joint solution”, they were left with no choice after David Frost’s announcement on 3 March to abandon the timetable for checks in the Northern Ireland protocol. It had been “crystal clear” to both sides that the protocol would entail “checks on some goods moving east, west from GB to NI” and that it had acceded to the UK’s request for grace period on checks last December. One official said that in exchange for an agreement on grace periods, the EU required the UK to provide a “road map” detailing how it would implement the NI protocol but this was never delivered by London. This road map was supposed to provide Brussels with a comprehensive plan for implementing the Northern Ireland protocol and the milestones that could be met through behind the scenes technical work and grace periods. The EU hopes the dispute can now be resolved through the specialised committee on Northern Ireland that sits beneath the UK-EU joint committee. Šefčovič’s letter to Lord Frost noted that Northern Ireland secretary, Brandon Lewis, announced that the UK would be extending the grace periods for checks on supermarket food until October “without any discussion or consultation with the EU”. Later that day it informed traders, in breach of the Brexit deal, that they could continue to send goods of animal origin, food, and animal feed and plant products from GB to NI without the need for any paperwork such as health certificates. The DUP said the legal action showed “Brussels’ claim to be protecting peace continues to ring hollow”. “Rather than showing concern for stability in Northern Ireland or respect for the principle of consent, Brussels is foolishly and selfishly focused on protecting its own bloc,” said party leader Arlene Foster.