The final report of the Convention on the Future of Europe will be "a highly influential starting point" for negotiations on a new EU Treaty between member state governments, the Taoiseach, Mr Ahern has said.
Rejecting criticism that the convention is being used by EU federalists to push their agenda, Mr Ahern said: "Designing a union that works effectively and a union that is more democratic and accountable is what we are about."
So far, the Government has been criticised for its attitude towards the convention, which is being regarded more seriously by other member states, particularly France and Germany.
However, Mr Ahern, giving an RTÉ Thomas Davis Lecture last night, said the Government has "from the outset, been fully engaged and is playing an active part" in the convention.
"We are working to ensure that Ireland's essential interests and values are reflected in the convention's outcome. There is little doubt that a never-ending circle of treaty change would not be in Europe's interest."
Describing the EU as "perhaps the greatest success story in the relations between free democratic countries", Mr Ahern said it is a model of political and economic cooperation that has no precedent.
An enlarged EU would present "new challenges, as well as opportunities", he said. Ireland's ability to adapt "will determine our future prosperity and success".
A 25-strong EU "will be very different from a union of 15", he said. "It will have a far greater population, be more diverse and have significantly different levels of economic development among its members."
