Taoiseach Leo Varadkar has said a no-deal Brexit would raise serious questions for the future of Northern Ireland.
Speaking at the MacGill Summer School in Glenties yesterday Mr Varadkar said in this scenario, people in Northern Ireland will question their union with England, Scotland and Wales.
"I do think that more and more people, certainly in the event of a no deal, more people in Northern Ireland will come to question the union.
"People who you might describe as moderate nationalists, or moderate Catholics, who are more-or-less happy with the status-quo will look towards a united Ireland.
"And I think increasingly you see liberal Protestants and unionists who will start to ask where they feel more at home."
Mr Varadkar went on to say that if the UK takes Northern Ireland out of the EU "against the wishes of the majority of the people there, takes away their EU citizenship and undermines the Good Friday agreement, those questions will arise whether we like it or not and we have to be ready for it."
Mr Varadkar indicated the Government would have to consider a forum on Irish unity in the event of a no-deal Brexit but said it would be "provocative" to do so now.
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"Having a green paper or forum on Irish unity now would be provocative.
"We have always been trying to make the point that what we are trying to achieve with Brexit and the withdrawal agreement is the status quo.
"People being able to continue to live their lives and trade as they do now."
He said some people would accuse the Government of trying to exploit Brexit to bring about a wider constitutional agenda.
"We would totally play into that view and that accusation if we were to go down the road now of having a white paper or forum on all Ireland unity."
He said that could obviously change in the event of a no-deal Brexit happening and those questions would arise.
His comments prompted a sharp rebuke from the Democratic Unionis Party, with MP Ian Paisley saying the language was "unhelpful and unnecessarily aggressive."
In the 2016 referendum, 56% in Northern Ireland voted to remain in the EU.
The 1998 Good Friday Agreement, which ended the violence, foresees the holding of referendums on both sides of the border on uniting the island if London and Dublin see public support for that. The British government says it does not believe there is sufficient support now.
Mr Varadkar also suggested voters in Scotland, where 62% voted to remain in the EU in the 2016 referendum, might make a new push for independence.
"Ironically one of the things that could really undermine the union - the United Kingdom union - is a hard Brexit, both for Northern Ireland and for Scotland. But that is a problem that they are going to have to face," he said.
Additional reporting: Reuters
