The Taoiseach, Bertie Ahern, is due to travel to Athens for an EU summit later today.
The leaders of the 15 current EU member states are due to use the occasion to sign a treaty allowing 13 new nations to join the union.
Ten of these states are due to join in May of next year, pending the outcome of their individual referendums on membership.
Mr Ahern is expected to hold talks with British Prime Minister Tony Blair about the Irish peace process on the fringes of the summit.