DUBLIN A return to border controls between Northern Ireland and the Irish Republic due to Britain's vote to leave the European Union cannot be ruled out, Ireland's foreign minister said on Monday after London laid out its Brexit timetable.
Northern Ireland, a British province, will be the only land frontier between the UK and the EU once Britain leaves. Both Dublin and London have insisted since the June vote that they do not want a return to border controls.
"That scenario cannot be ruled out," Charlie Flanagan told Newstalk radio when asked if the border could be back by 2019 after British Prime Minister Theresa May said she would begin the two-year process to leave the EU by the end of next March.
"The reimposition of a heavily fortified or hard border would present a great challenge... This is a matter of great concern to everyone on this island."
The frontier was marked by military checkpoints until a 1998 peace deal ended three decades of violence between Catholic nationalists seeking a united Ireland and Protestant unionists who wanted to keep Northern Ireland British. Over 3,600 died in that time.
The Irish economy is seen as most vulnerable to the knock-on effects of Brexit. Dublin has been seeking support from other EU countries to preserve the freedom of movement and goods across the island and is hoping a system of electronic border surveillance will prevent it having to erect physical barriers.
Flanagan said he was not discouraged by meetings with British government ministers whom he said understood the issue. But he urged that they set out their negotiating priorities over the coming weeks before the formal process starts.
"This is the greatest foreign policy challenge that Ireland has had since we joined the EEC (European Economic Community) 43 years ago," Flanagan told national broadcaster RTE in a separate interview.
(Reporting by Padraic Halpin and Conor Humphries; Editing by Hugh Lawson)