The Taoiseach, Leo Varadkar, has said the British Government is wrong and in breach of the Good Friday Agreement in its insistence, against her wishes, that Co. Derry woman Emma DeSouza is British rather than Irish.
The DeSouza case was raised by the Sinn Féin leader Mary Lou McDonald in the Dáil this week.
She said it "cuts to the chase in respect of citizenship rights and the recognition of Irish nationality".
"The Taoiseach is familiar with the case. Can he confirm whether it has been the subject of discussions between the Irish State and Britain and what remedy he has secured for Irish citizens living in the North?" she asked.
The Taoiseach was unequivocal in his response.
"The GFA is explicit that people in NI are entitled to be British, or Irish, or both, and are accepted as such.
"I think the British Government has got it wrong in this case and the matter has been raised in our bilateral conversations.
"I have raised it with the Prime Minister, and the Tánaiste has raised it too.
"While we respect that the British have their own courts system, the GFA is clear in both letter and spirit and I think the UK Government has got it wrong in that case," said the Taoiseach.