The Taoiseach insisted today that Ireland’s approval of the Treaty of Nice was essential to allow 10 applicant states into the community.
Speaking at the Forum on Europe in Dublin Castle, Mr Ahern said: "It should be very clear that ratification is essential for enlargement. "Anyone who still suggests otherwise is deliberately trying to create confusion. Until Ireland ratifies the Nice Treaty, our partners, present and future, can have no certainty.
"Nice is also necessary to enable the new and enlarged union to conduct its business effectively and efficiently," he said.
The Nice Treaty was rejected in a referendum last June. Critics of the treaty afterwards claimed expansion of the EU, involving the possible entry of up to 10 new members, could still go ahead without Irish endorsement of the Nice document.
Mr Ahern said: "It would be wrong for Ireland to block progress on perhaps the largest and most important initiative that the Union has ever undertaken. I do not believe that the Irish people want to do this."
Mr Ahern will depart for tomorrow's European Council session in Laeken, Belgium, which is scheduled to focus on Europe's future.