Taoiseach Micheál Martin said new European Commission proposals to overcome difficulties with the Northern Ireland protocol will "pave the way for a very serious engagement" and represent "a very significant opportunity".
Mr Martin said EU chief Brexit negotiator Maros Sefcovic briefed him ahead of the publication of the "comprehensive"proposals.
"I now believe that the United Kingdom government should engage with the European Commission on this package of proposals and should work jointly with the European Union to arrive at a joint solution in relation to this issue."
Mr Martin said the proposals demanded an equivocal response from the UK which should commence now. “This demonstrates beyond a shadow of a doubt that the European Commission is in solution mode.”
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The British government said it will study detail of the commission’s proposals and would look at them seriously.
“The next step should be intensive talks on both our sets of proposals, rapidly conducted, to determine whether there is common ground to find a solution,” said a Downing Street spokesman.
“Significant changes which tackle the fundamental issues at the heart of the protocol, including governance, must be made if we are to agree a durable settlement which commands support in Northern Ireland.
"We need to find a solution which all sides can get behind for the future, which safeguards the Belfast Agreement and which puts the UK-EU relationship on a stronger footing. We are ready to work hard with this in mind."
Earlier this week, Britain submitted legal texts to the commission based on last July’s command paper calling for sweeping changes to the protocol. Elements of Britain’s proposal, such as introducing a dual regulation system for goods circulating in Northern Ireland and removing the enforcement role of the European courts, would require changes to the text of the protocol.
Northern Ireland reaction
DUP leader Jeffrey Donaldson was downbeat on the proposals. He said they “clearly fall a long way short of being the basis of a sustainable solution” and again called for the protocol to be replaced.
The EU needed to “redouble their efforts” in negotiations with the UK “to replace the protocol with new arrangements”, he said.
Northern Ireland Deputy First Minister and Sinn Féin deputy leader Michelle O’Neill said the commission’s proposals are a “mark of progress, but it is up to others now as to whether they engage with the process.”
SDLP leader Colum Eastwood said the proposals offer a "clear landing zone" after turbulence over the protocol. He urged unionist leaders to embrace the compromises.
UUP leader Doug Beattie said the EU "has moved significantly, something many told us was not possible".
Earlier, British prime minister Boris Johnson's former chief adviser Dominic Cummings said the government had always intended to "ditch" the protocol.
Mr Cummings, who was at the meeting between Mr Johnson and Leo Varadkar in October 2019 which agreed the protocol framework, said the deal was done against the background of a constitutional crisis.
“So we wriggled [through] with the best option we [could] and intended to ditch bits we didn’t like after whacking Corbyn,” he said. “It was international diplomacy vs people trying to cut our balls off. Of course there wasn’t ‘good faith’ ... cheating foreigners is a core part of the job.”
Mr Cummings said his claims did not mean that Mr Johnson was lying when he agreed to the protocol because “he never had a scoobydoo what the deal he signed meant”.
