Taoiseach Leo Varadkar has reminded the UK that commitments entered into in December on avoiding a hard border would have to be adhered to.
Speaking in Davos, Mr Varadkar said: "We have an agreement, a set of commitments, that were reached in December.
"We fully expect them to be reflected in the legal text of the withdrawal treaty, and I don't see why the UK would want to depart from what they agreed to in December in any way.
"It doesn't put you in a strong position in negotiations if you're agreeing things in December and then trying to depart from them in January or February."
The commitments contained in the joint report on the Irish border, and agreed by EU and UK negotiators in December, are due to be translated into binding legal texts in the coming weeks.
This will allow those commitments, or guarantees, to be embedded in the Withdrawal Treaty governing the UK's departure from the European Union on 30 March 2019.
In the joint report, the UK committed to maintaining full alignment on the rules of the single market and customs union as regards Northern Ireland if other solutions to avoid a hard border do not work.
The report also declared that there would be no difference between Northern Ireland and the rest of the UK in this regard.
However, senior British cabinet ministers have spoken of gradual regulatory "divergence" from EU rules.
These contradictions will require resolution ahead of the guarantees being converted into legal texts.
The EU is expected to start that process in the coming weeks.
Meanwhile, the Taoiseach welcomed recent remarks from the Confederation of British Industry calling on the UK to remain in the customs union.
Speaking to reporters at the Swiss ski resort, Mr Varadkar said: "I'm very encouraged by what I'm hearing from British business, and that includes civil society in the UK who are very much saying they want to have a very close relationship with the European Union.
"The best way for us as Ireland to resolve our issues, the question of the border and the need to protect free trade between Britain and Ireland, the best way for that to be resolved is in the context of a very close agreement, a new partnership between the UK and the EU. And that is possible. It can be a very close partnership.
"The relationship between the Irish and British governments is very good. We're aligned on more things than what we differ on.
"Brexit has strained relations somewhat, but in the broader vein and the bigger picture relations are very close, there is more that unites us than divides us in that regard."
'Norway plus' model for UK may be possible
Earlier, the Taoiseach hinted that the UK could get a bespoke trade agreement with the EU after Brexit.
Speaking on Bloomberg TV, Mr Varadkar said he hoped that the ultimate free trade arrangement could resemble "Norway Plus", but that it would have to be a "specific" agreement.
The kind of Free Trade Agreement (FTA) envisaged has generally been regarded as following a spectrum between the EU-Canada agreement, which reduces tariffs but has little by way of services, and the EU-Norway arrangement, where Norway has virtually full access to the Single Market, but has to abide by all EU rules and pay into the EU budget.
However, Mr Varadkar said that neither Norway nor Canada were appropriate models.
He said: "It’s difficult to speculate. It’ll be a new agreement between the UK and the EU. Britain is a big place. It is 60 million people, compared to Norway which is a relatively small country like Ireland, or a country like Canada, which is on a different continent.
"It will be a specific agreement for the UK, but of course as Ireland we want that to be as close as possible, so we would have it as ‘Norway Plus’ but I think we need to get into the detail now as to what that means. It’s been some time now since the referendum happened.
"We need to get down and dirty with the detail."
The Taoiseach, who is accompanied by Minister for Finance Paschal Donohoe, is doing a series of interviews with global news networks as well as meeting a number of senior executives, including - it is understood - Sheryl Sandberg of Facebook, and Brian Moynihan, CEO of Bank of America.
Mr Donohoe took part in a debate on tax avoidance with Pierre Moscovici, the EU's commissioner for economic and financial affairs, and Winnie Byanyima of Oxfam, a staunch critic of Ireland's corporate tax policies.
Eighth Amendment question 'has to be sound'
Mr Varadkar has said he hopes Cabinet will agree to proceed with a referendum on the Eighth Amendment following a special Cabinet meeting on the issue on Monday evening.
He said he did not want to shoe horn the issue into an agenda of 30 items, and for that reason he decided to convene a special Cabinet meeting.
"I will certainly give my views on that after the Cabinet meeting if we have an agreement," he added.
Mr Varadkar said the question that is put to the Irish people has to be sound and has to be one that the Attorney General can endorse.
He said, respecting the fact that there is a free vote, he wanted to bring his Cabinet and his party with him, in as much as he can.
Varadkar concerned over Opposition proposals on property
Mr Varadkar said he does not believe there is a property bubble in Ireland and while residential property prices are rising, he said they are still lower than they were ten years ago.
He also said there is huge growth in commercial property.
"You only have to walk the streets of Cork, or Limerick, or Dublin, to see the amount of new properties under construction," he said.
The Taoiseach acknowledged, however, that Ireland has had, what he described as a lost decade.
He said he was very concerned to hear "a voice from the Opposition" calling for measures that led to the crash, such as more public spending that may not be affordable, tax breaks for developers and the Government offering 97% mortgages.
"I'd be much more worried about the Opposition not having learned the mistakes of the past, than any current problems," he said.