The British Prime Minister Theresa May has said any decision on a hard Irish border, due to a no-deal Brexit, could be largely out of Britain's control.
She has been taking questions on the Brexit deal from senior MPs on the House of Commons Liaison Committee.
The role of the committee is to take evidence from the prime minister on matters of public policy - usually three times a year.
It comes after the Bank of England warned leaving the EU without an agreement could lead to economic collapse.
Asked about any scenario that could see a hard border, Mrs May said it is mostly out of their control.
"We have said that we would do everything in our power not to exercise, not to have a hard border.
"But we are not the only party to this arrangement: obviously there is the Irish Government - in fact, competence in this is a matter for the European Union.
"As the Taoiseach has made clear - sometimes it's said to me 'Well, everybody says they won't have a hard border' - but the point he's made is you can't just rely on political statements for no hard border, you to actually have the arrangements in place that enable no hard border to be erected".
UK PM Theresa May appears before the House of Commons Liaison Committee | © Parliamentary Copyright
"In the no-deal scenario, we would do everything we could not to erect a hard border - but there would be a decision from the European Union and the Irish Government.
"And the concern that they would have would be about the fact that we would then be in a different set of circumstances on customs and so forth, and how do you check those?".
Rejecting the suggestion of a second Brexit referendum, Mrs May said: "The most important reason why we should not be going the route of a second referendum is that we asked the British people, they've give us their view and we should deliver on that view.
"There are different views as to how we should deliver on that view - but I believe that we should deliver on it.
"I believe we owe it to the British people, having given them the choice to actually make that choice happen for them".
But one MP suggested: "I'm afraid it would be, in my view, a bit like wheeling someone into the operating theatre - based on a consent form they'd signed two years ago - without really knowing what the operation was and being able to give proper, valid, informed consent after weighing up the risks and benefits of the actual operation".
Mrs May's deal has reportedly gained support from the prominent Brexiteer and Commons leader Andrea Leadsom.
While UK Labour has tabled an amendment to the government's motion to approve Mrs May's Brussels agreement in an attempt to block it.
Jeremy Corbyn announced the move as the government revealed that MPs will have 40 hours - five days of eight hours - of debate, starting on December 4th, with the final vote on December 11th.
MPs will be able to put down six amendments to the government's Brexit motion and House Speaker John Bercow will select the amendments to be debated and voted on.
Additional reporting: IRN
