DUBLIN, May 1: Leaders from old and new European Union states hailed the reunification of their continent on Saturday with prayers, poems and parties and the raising of 25 national flags.

"Today marks the triumph of determination and perseverance over the legacy of history," Irish Prime Minister Bertie Ahern said, referring to the EU entry of the ten new states, of which eight are ex-communist nations.

But the premier also insisted that the 25 countries must urgently clinch agreement on a new constitution aimed at streamlining decision-making in an expanded EU.

"There will be enormous difficulties if we try and continue in the way we are going," Mr Ahern said.

European Commission President Romano Prodi argued in favour of increased majority-voting in the bloc's council of ministers, warning that the current unanimity rule would bring the enlarged EU to a screeching halt.

Negotiations on a new EU treaty broke down in acrimony in December after Spain and Poland refused any downgrading of their voting rights.

Ireland, as current EU president, has been trying to revive the talks, with negotiations set to resume at the level of foreign ministers in Brussels on May 17.

Mr Ahern has said he wants the EU summit in mid-June to seal agreement on the treaty.

"A way forward can be found with the necessary political will," he said.