The Tánaiste Simon Coveney has admitted avoiding a hard border would be more complicated in the event the Brexit deal, agreed by EU leaders, is rejected in the UK.
It comes as Theresa May faces the Commons after EU leaders endorsed the deal and made it clear it was not up for renegotiation.
The British Prime Minister will challenge MPs to back her Brexit plan or risk crashing out of the European Union without an agreement, telling the Commons "with absolute certainty" that "there is not a better deal available".
The Prime Minister, who is conducting a meeting of her Cabinet this morning, will warn rejecting her deal will "open the door to more division and uncertainty, with all the risks that will entail".
Mr Coveney said a British rejection of her Brexit deal would create challenges in a number of areas.
He said: "The consequences in lots of areas, not just in terms of the challenge to prevent border infrastructure, but so many other areas too in terms of the relationship between the UK and the EU in the absence of this deal passing is going to be much more complicated and far less attractive, I can assure you of that."
- Digital Desk