The Republic's finance minister has said it is evident that the new British government wants scope for regulatory divergence from the EU whether or not there is a deal.
Paschal Donohoe told the DCU Brexit Institute that this is clear from the letter Prime Minister Boris Johnson wrote to the President of the European Council Donald Tusk last month.
"The challenges and opportunities that Ireland will face in the medium term will be heavily influenced by how far the United Kingdom decides to diverge from the European Union," he said.
"While the Irish government will absolutely respect the choice of the British government to pursue a path of regulatory divergence from the EU, there are clear implications for this island and the Good Friday Agreement that cannot be ignored in the event that this becomes its policy."
Mr Donohoe added: "The UK's departure from the EU poses an unprecedented challenge for the island of Ireland, and for Northern Ireland in particular.
"In the Brexit negotiations we have insisted on protecting the cooperation on our island between north and south that flows from and underpins that Good Friday Agreement – an agreement that saves lives.
"The EU and UK agreed the 'backstop' on the basis of a shared understanding of the need to address the unique circumstances of Northern Ireland to provide the guarantee necessary to reassure a concerned public.
"Some have expressed concerns that the Withdrawal Agreement and the Protocol on Ireland/Northern Ireland go against the principle of consent contained in the Good Friday Agreement. This is not the case.
"The first line of the protocol, and the first clause of the backstop, reaffirm very clearly the principle of consent.
"No-one wants to see the unintentional loss of enormous benefits that the border as it is now – seamless, unobtrusive and barely perceptible – brings to businesses and families on this island."
"I understand the fears that some in the Unionist community have expressed about the backstop," Mr Donohoe added.
"The government takes these concerns very seriously, as we do the concerns of everyone who is troubled by Brexit and its potential impacts on both parts of our island.
"However, the backstop should not be viewed as a challenge to unionism.
"Its purpose is to provide certainty to businesses and communities on both sides of the border that they will be able to continue to operate and go about their daily lives as they do today. Nothing more.
"It represents a compromise – it is not the status quo.
"It is not the same as Northern Ireland staying in the EU."
The European Commission said proposals to replace the Irish backstop "have not yet been made" by Boris Johnson.
In a statement following the talks, the commission said: "President Jean-Claude Juncker and Prime Minister Johnson had a working lunch today in Luxembourg.
"The aim of the meeting was to take stock of the ongoing technical talks between the EU and the UK and to discuss the next steps.
"President Juncker recalled that it is the UK's responsibility to come forward with legally operational solutions that are compatible with the Withdrawal Agreement.
"President Juncker underlined the Commission's continued willingness and openness to examine whether such proposals meet the objectives of the backstop. Such proposals have not yet been made."
European Parliament chief Brexit co-ordinator Guy Verhofstadt tweeted: "The UK gov't rejected 3 EU proposals on Ireland: the current backstop, the NI-only backstop & avoiding any other backstop by making the Political Declaration more binding.
"Time for the UK gov't to make up its mind or propose a serious, concrete alternative."
Mr Bettel, answering questions from reporters, said: "For me I just have one Withdrawal Agreement on the table and it's the one from last year.
"There are no changes. There are no concrete proposals for the moment on the table. And I won't give an agreement to ideas. We need written proposals and the time is ticking."
Mr Bettel told Mr Johnson to "stop speaking and act", adding: "But we won't accept any agreement that goes against a single market, who will be against the Good Friday Agreement."
He added "solidarity" with Ireland is "strong" before noting: "This Brexit it's not my choice.
"It's been a decision from a party, a decision from David Cameron to do it. They decide, I deeply regret it but don't put the blame on us because now they don't know how to get out of this situation."
Boris Johnson has reiterated his determination to get Brexit done by the October 31 deadline "deal or no deal" after meeting with Jean-Claude Juncker.
The PM said the EU must make "movement" in its opposition to scrap the Irish backstop, but insisted there is "just the right amount of time" to get a deal done.
Mr Johnson was asked what concrete proposals he had put on the table.
"Over the last couple of weeks there's been a lot of work, papers have been shared but we are now in the stage where we have to start really accelerating the work. That was the agreement today," he said.
"We've got to manage this carefully. Yes, we've got a good chance of a deal. Yes, I can see the shape of it. Everybody could see roughly what could be done.
"But it will require movement. And it will require the system in which the EU can control the UK after we leave - the so-called backstop - to go from that treaty. And that needs to happen. That's a big change that we need to get done. But if we can get that done, as I've said before, then we're at the races.
"I think we've got actually just the right amount of time to do a deal between now and October 17-18. But if we can't do it by then we will make sure we can come out on October 31 - deal or no deal."
