Michelle O’Neill, Sinn Fein’s leader in the region, said the UK government was “on the verge of triggering Article 50 that is going to take the North out of the EU against the expressed wishes of the majority of people here”.
She added: “They are continuing to refuse to listen to the majority views. Brexit would be a disaster for the economy and the people of Ireland.
“To us in Sinn Fein that increases the urgency for the need of a referendum on Irish unity and that needs to happen as soon as possible.”
Irish Foreign Affairs Minister Charlie Flanagan said calls for an Irish border poll were “premature” and an issue for the longer term.
Mr Flanagan, who is taking part in political talks at Stormont in a bid to restore powersharing, said the focus must be on getting the institutions up and running first.
“I don’t think there is an area from here to the Baltic Sea, or from there to the Black Sea, or from there to the Mediterranean Sea, that is as potentially adversely affected by the withdrawal of the UK from the EU as is here in Northern Ireland and I think it is important therefore that we have a fully functioning Executive up and running to deal with this challenge at the earliest opportunity - this day fortnight,” he said.