Any effort to control the free movement of people across the Border, or between Britain and Ireland, would be "very damaging", Ireland's Ambassador to Britain, Dan Mulhall, has told a House of Lords committee.
Mr Mulhall said the open border had come about as a result of the peace process and Britain and Ireland’s shared EU membership.
"The current Border arrangements are of benefit to both parts of Ireland and to all our communities and need to be preserved, with the avoidance of a hard border. I am encouraged by the statements from Belfast and from the government here in London, most recently by the secretary of state for exiting the European Union in his statement yesterday, that this view is shared by all of us."
Mr Mulhall said he believed other EU states understood the unique issues Brexit raised for Ireland, and they were willing to be sensitive to any concerns that could arise for Northern Ireland.
The ambassador was appearing before the House of Lords European Union committee which is looking into the potential impact of Brexit, including on UK-Irish relations.
