A bid to give Northern Ireland special designated status within the EU after Brexit has been defeated in the European Parliament.
A bloc of left-wing parliamentarians, of which Sinn Féin is a part, proposed the measure in Strasbourg.
It was defeated by MEPs by 374 votes to 66.
DUP MEP Diane Dodds said: "Ultimately, this week's vote by MEPs is further demonstration that Sinn Féin's Brexit charm offensive has failed miserably."
The republican party's demand for special designated EU status for Northern Ireland post-Brexit has raised unionist concerns that their real motive was to drive a wedge between the North and the rest of the UK.
The fact Brexit has now been caught up in a reignited debate about a united Ireland has also polarised the issue.
The amendment to legislation in the European Parliament said the 1998 Good Friday Agreement, which largely ended the violence and subsequent agreements, should be fully upheld in the withdrawal agreement.
It said special EU status would also ensure membership of the Customs Union, Single Market and the jurisdiction of the European Court of Justice.
It also called for the freedom of movement of goods, people and services on the island of Ireland.
Mrs Dodds said the proposals would have prevented Northern Ireland from harnessing new opportunities which flow from Brexit as an integral part of the UK.
"Critically, it would also cut us off from the Great Britain market - by far the most importance marketplace for local goods and services from Northern Ireland."
Nationalists have argued retaining special designated status would ease all-Ireland trade.
Concerns over a hard border post-Brexit have exercised minds in Belfast, Dublin, London and Brussels, with a series of high-level promises to try and minimise its impact.
Ulster Unionist MEP Jim Nicholson said the amendment was "roundly rejected" by the Parliament.