Deputy First Minister Martin McGuinness has said he cannot see how the common travel area on the island of Ireland can survive in the forthcoming Brexit negotiations.
He was speaking as he and First Minister Arlene Foster attend a specially convened meeting of the British Irish Council in Cardiff on Wednesday.
The summit, which includes representatives from the British and Irish governments as well as the devolved administrations, has been called to discuss the implications of the EU referendum result.
The Sinn Féin politician said it was an “extremely disappointing” situation.
Northern Ireland Secretary of State James Brokenshire said there is a “strong will” on the part of the British and Irish governments to prevent a “return to those border issues”.
Arlene Foster said she hoped all involved in negotations would work together to achieve the best for each region.