TAOISEACH Micheál Martin has said legal proceedings initiated by the European Commission against the UK were "to be expected".
He said the British government was "under no illusions" about the strength of opposition to legislation overriding key elements of the Withdrawal Agreement, but he was still hopeful talks on a trade deal could get to a more "intense phase over the next week or so".
The comments followed a meeting with commission President Ursula von der Leyen, after Mr Martin travelled to Brussels for a special meeting of the European Council yesterday.
Ms von der Leyen said a "letter of formal notification" would be sent to the UK as the first step in an "infringement procedure" after it rejected a demand to withdraw provisions from the Internal Market Bill by the end of September.
She gave no indication about what action could follow, although under the terms of the Withdrawal Agreement the EU could take Britain to the European Court of Justice.
A British government spokesman said they would respond "in due course".
"We have clearly set out our reasons for introducing the measures related to the Northern Ireland protocol.
"We need to create a legal safety net to protect the integrity of the UK's internal market, ensure ministers can always deliver on their obligations to Northern Ireland and protect the gains from the peace process."
Mr Martin said the Irish government supports the commission in its actions.
The Fianna Fáil leader told RTÉ there is "concern" across Europe at the unilateral action by the British government on the Northern Ireland protocol and the UK Government needed to "resile" from that.
"Parallel with that we are conscious of the need to conclude a comprehensive relationship agreement with the UK which is in the best interests of the people of Europe, the UK and Ireland," he said.
While Mr Martin said he was hopeful that talks would become more intense he also cautioned that the issues were "very substantive".
DUP parliamentary leader Sir Jeffrey Donaldson accused the EU of using Northern Ireland "as a bargaining chip to secure favourable trade terms" and said the Prime Minister "was right to protect the integrity of the UK's internal market".
"The Internal Market Bill in and of itself does not breach international law," he said.
But SDLP leader Colum Eastwood described the British government's position as "a bad faith breach of responsibilities entered into by Boris Johnson a year ago" and said he should withdraw the bill.
Sinn Féin president Mary Lou McDonald also welcomed "the EU is taking action to confront unacceptable British government threats to breach international law" and said it "reflects the dismay felt internationally at Britain’s behaviour over Brexit".
Alliance MP Stephen Farry said the commission's action "was the inevitable consequence of the UK’s refusal to remove its outrageous and extraordinary threat of breaching the terms of the existing Withdrawal Agreement and international law".
Patrick Corrigan of Amnesty International also said the legal proceedings are "a welcome attempt to ensure that the UK abides by its international treaty commitments", claiming the bill "fundamentally undermines the Belfast/Good Friday Agreement and the principle of no diminution of rights and equality safeguards".
