A spokesman for Taoiseach Leo Varadkar has said both Ireland and the EU will be holding the UK to the Phase 1 agreement reached this week.
It comes as Britain's Brexit minister David Davis described the UK government's pledge to prevent any return to a hard border with Ireland after Britain leaves the EU as "a statement of intent" rather than a legally binding move.
The government spokesman cited in particular Article 46 which states that: "The commitments and the principles...are made and must be upheld in all circumstances, irrespective of the nature of any future agreement between the European Union and the United Kingdom."
The spokesman said that "as the Taoiseach indicated on Friday, even if the worse case scenario occurs and there is no final deal, there must still be full alignment north and south under the agreement".
An initial deal to move Brexit talks to a second phase was secured this week, by agreeing terms on how much Britain should pay to leave the EU, on citizens' rights and the border issue, where London agreed a fallback of regulatory "alignment" with the EU.
"This was a statement of intent more than anything else," Mr Davis said.
"It was much more a statement of intent than it was a legally enforceable thing," he told the BBC's Andrew Marr show.
Speaking on RTÉ’s This Week programme, the Government Chief Whip Joe McHugh said while the UK and the EU explored possible trade deals in the next phase of Brexit talks, the Irish position would be protected by Friday's agreement which was binding in principle.
Asked how that could be reconciled with Mr Davis’ remarks, Mr McHugh questioned what was the point of the UK signing up to an agreement if it was not going to uphold it.
He said the Government and the EU would hold the UK to account to deliver on the commitments made last Friday.
Mr McHugh said there will be lots of "rhetoric" and noise about the agreement and he was not going to be drawn into the internal issues in British politics.
"There has been a lot of bruising over the last fortnight," he added.
He insisted the Irish Government and the EU will not be backing away from the agreement.
Art.46 of Fridays agreed text re Ireland/NI: "The commitments and the principles...are made and must be upheld in all circumstances, irrespective of the nature of any future agreement between the European Union and the United Kingdom." - clear and positive commitment from UK Govt— Simon Coveney (@simoncoveney) December 10, 2017
Mr Davis also said Britain will not pay a €44 billion exit bill to Brussels if it does not secure a trade deal.
The comments appeared to contradict those of UK Chancellor Philip Hammond who has said it would be "inconceivable" that the UK would fail to honour its international obligations.
Pressed on Mr Hammond's remarks regarding the exit payment, Mr Davis said: "No. It is conditional on an outcome. I am afraid that wasn't quite right.
"It is conditional. It is conditional on getting an implementation period. Conditional on a trade outcome.
"No deal means that we won't be paying the money."
Asked if Mr Hammond was wrong, Mr Davis said: "It has been made clear by No 10 already. So that's not actually new."
When asked at a Commons Treasury Committee meeting this week whether Britain's divorce bill was contingent on a trade deal, Mr Hammond said: "Nothing is agreed until everything is agreed in this negotiation.
"But I find it inconceivable that we as a nation would be walking away from an obligation that we recognised as an obligation.
"That is not a credible scenario. That is not the kind of country we are. Frankly, it would not make us a credible partner for future international agreements," said Mr Hammond.
Mr Davis said the chances of Britain leaving the EU without a trade deal have now "dropped dramatically".