The Democratic Unionist Party has slammed the appearance of the so-called Colombia Three at Sinn Féin's Ard Fheis in Dublin over the weekend.
James Monaghan, Martin McCauley and Niall Connolly all attended the conference despite still being wanted by the Colombian authorities for allegedly training FARC rebels in bomb-making techniques.
The three men fled Colombia after their acquittal on the charge was overturned on appeal.
DUP MEP Jim Allister is now demanding to know why the Gardaí did not arrest them at the Ard Fheis and has pledged to raise the matter at EU level.
He also said the Irish authorities' failure to send the men back to Colombia was a damning indictment of the Irish legal process.