The European Parliament has postponed a decision on ratifying the EU-UK free trade agreement in protest at the UK's unilateral move on how the Northern Ireland Protocol should be implemented.
The Trade and Cooperation Agreement (TCA) was concluded by the EU and UK on 24 December, but it has only been applied provisionally because of a lack of time for both member states and the European Parliament to follow ratification procedures.
The European Parliament was expected to finally ratify the treaty on 24 March.
However, according to sources, senior officials in the parliament have decided to delay a decision on when to ratify the TCA.
An item on ratification does not appear on the draft agenda of the plenary session due on 24-25 March as seen by RTÉ News.
Meanwhile, the European Commission has said that the EU could bring infringement proceedings against the UK as a result of the unilateral action.
A spokesman told RTÉ News: "A breach of the obligations under the Protocol on Ireland/Northern Ireland would allow the EU to have recourse to the legal remedies available under the Withdrawal Agreement.
"This involves, as a first step, bringing an infringement proceeding in the specific cases provided for by the Protocol (Article 12(4)). Work on legal action is currently ongoing."
The spokesman said the UK move amounted "a violation of substantive provisions of the Protocol on Ireland/Northern Ireland and the good faith obligation under the Withdrawal Agreement".
In a strongly worded statement last night, the European Commission said the UK was in breach of the good faith provision of the Withdrawal Agreement, and was set to breach international law for a second time.
Last September, Northern Ireland Secretary Brandon Lewis told the House of Commons that the UK would breach international law by taking unilateral action on the protocol through the Internal Market Bill.
Minister for Foreign Affairs Simon Coveney has said the EU is negotiating with a partner it simply cannot trust.
He said the UK move is really unwelcome and it is the "British government essentially breaking the protocol" and its own commitments again.
However, Downing Street has rejected Mr Coveney's assessment.
British Prime Minister Boris Johnson's official spokesman said: "We have worked closely with the EU throughout the Brexit period, not just in terms of the Northern Ireland Protocol but with regards to the TCA that we agreed at Christmas time.
"We continue to work closely with them through the Joint Committee process and remain committed to the Northern Ireland Protocol but we want to address those areas where there are issues that have arisen."
The spokesman insisted Brussels and Dublin had been informed in advance about the action the UK was taking.
"We notified the European Commission at official level earlier this week," he said.
"We also informed the Irish government earlier this week and then Lord Frost last night in his call to (European Commission vice-president Maroš) Šefčovič obviously discussed this at length and set out the rationale and the reasons for it."