Irish have voters rejected the European Union's Lisbon treaty, putting plans to overhaul the bloc's institutions in peril and humiliating Ireland's political leaders.

Justice Minister Dermot Ahern conceded the vote shortly after midday on Friday as tallies from around the country showed the treaty had been defeated in an overwhelming number of constituencies.

"It looks like this will be a 'No' vote," Ahern told RTE television. "At the end of the day for a myriad of reasons the people have spoken."

The Lisbon treaty was itself an effort to resurrect EU reforms that were torpedoed by French and Dutch voters in 2005.

This time Ireland was the only country to entrust its voters with a referendum. The "No" vote means a country with fewer than 1 percent of the EU's 490 million population could doom a treaty painstakingly negotiated by all 27 member states.

The Lisbon treaty envisages a long-term president of the European Council of EU leaders, a stronger foreign policy chief and a mutual defence pact. Fourteen countries have already ratified the treaty in their national parliaments.

But while Ireland ranks in surveys as one of the EU's most pro-European states, opponents say the treaty reduces small countries' influence and gives Brussels new foreign and defence policy powers that undermine Ireland's historic neutrality.

With more than 864,000 votes counted, official returns from Thursday's vote showed "No" leading 53.85 percent to 46.15 percent.

EURO FALLS

The euro fell to its lowest level in over a month against the dollar after the first reports suggesting a "No" victory.

EU leaders meeting in Brussels next week will have awkward questions for Ireland's Prime Minister Brian Cowen.

Some expressed hope that Ireland would still find a way to sign on to the pact.

"Ireland will for sure find a way to ratify this treaty," Polish Prime Minister Donald Tusk told reporters.

French officials have said work on the treaty could continue. France assumes the rotating EU presidency in a matter of weeks and was supposed to be in charge of setting up the new system which would take effect at the start of the year.

The British government, which faces a strong Euro-sceptic political opposition that has demanded its own referendum, has said plans to ratify the treaty would go on regardless.

But Mary Lou McDonald, a member of the EU parliament from Ireland's nationalist Sinn Fein party, which helped lead the victorious "No" campaign, said it would be impossible for Irish leaders to wriggle out of the referendum result.

"This is a moment of democratic truth here. Do you listen to the people or don't you?"

The treaty had the backing of the three main political parties in Ireland, which has prospered under EU membership. Farmers groups, businesses and many labour unions also backed it.

On polling day bookmakers were still taking bets giving it overwhelming odds to pass.

It wasn't the first time Irish voters have shocked the EU. They almost wrecked the bloc's plans for eastward expansion in 2001 by rejecting the Nice treaty, but the government staged a second referendum in which that pact passed. The government has said it is not considering a re-run this time around.