The citizenship referendum in the 26 Counties has caused political damage to the Good Friday Agreement, nationalists have warned.
Constitutional changes were overwhelmingly supported in the vote on tightening immigration laws.
The electorate voted by four to one in favour of the switch, removing the right for parents of children born on the island of Ireland to claim citizenship. Total turnout was just under 60 per cent.
The ‘yes’ vote came in at 79 per cent, with 21 per cent against.
The outcome was little surprise asthe electorate reacted strongly to warnings that floods of illegal immigrants would use the birthright clause of the constitution as a backdoor to Ireland and Europe.
The right to citizenship was put in place as part of the 1998 Good Friday Agreement as a concession to northern nationalists, and its removal has added to feelings that the Agreement is unravelling.
Sinn Féin vice president Pat Doherty said: “The outcome of the poll would give unionists in the north the ammunition to argue that the 1998 Good Friday Agreement could be altered. The Paisleyites will use this. It’s the ideal argument that if the government can change the Good Friday Agreement, why can’t they?”
SDLP leader Mark Durkan also said the referendum had caused political damage to the agreement.
“Before the referendum we received assurances from the government that nobody born before June 11 and none of their children born after that date would be deprived of Irish citizenship by the referendum,” he said.
“We will now work to ensure that all other children born in the north can get Irish citizenship on the exact same terms as children born in the south.”
Labour’s justice spokesman Joe Costello said the Dublin government had used scaremongering tactics to win support for the vote. He expressed concern that the agreement could be affected in the short term and long term.
“This is a change of one of the basic tenets of the Good Friday Agreement and there’s no sense in pretending otherwise,” Mr Costello said.