Ireland voted overwhelmingly to ratify the EU's Lisbon Treaty in a second referendum, overturning a previous No vote and taking a key step towards ending the expanding bloc's deadlock, leaders said on Saturday.

Irish Prime Minister Brian Cowen called the decisive Yes vote, with 67 percent support, "a good day for Ireland and... a good day for Europe", as his EU counterparts hailed a crucial development for its future.

In Brussels, European Commission chief Jose Manuel Barroso thanked the Irish people "for this sign of confidence," saying it "showed that the European Union was ready to listen" to the misgivings which led to last year's No vote.

Official results showed 67.13 percent in favour compared to 32.87 percent opposed, with turnout of 58 percent.

In a first referendum in June 2008, Irish voters had stunned the EU by rejecting the reform treaty -- designed to streamline decision-making -- by 53 percent.

A second No vote would have effectively killed the treaty, which notably creates a new full-time president and foreign minister for the 27-nation EU, home to some 500 million people.

But in Friday's poll, held against the backdrop of an economy in deep recession, the treaty was backed by 41 of Ireland's 43 constituencies.

Cowen said: "Today the Irish people have spoken with a clear and resounding voice. We will now work with all our partners in ensuring the reforms this treaty will bring are implemented."

The No camp conceded defeat even before official results were published in Ireland, the only EU country constitutionally obliged to put the treaty to a referendum.

"The Irish people have asserted their trust in the political establishment of this country who have promised them jobs for a Yes vote and economic recovery," said Declan Ganley, who led the victorious No campaign last year.

Dublin agreed to hold another poll after securing guarantees on key policy areas which it felt were behind last year's rejection, such as its military neutrality, abortion and tax laws.

Govt in trouble

But there had been concerns that voters would use the referendum to punish Cowen's increasingly unpopular government over the spectacular collapse of Ireland's long-booming economy.

Even with the Irish Yes, further obstacles remain: while 25 EU states have now formally backed the Lisbon Treaty, Poland and the Czech Republic have yet to ratify it.

In Prague on Friday, the Czech constitutional court ordered President Vaclav Klaus -- who in any case is a fierce opponent of the treaty -- to hold off signing it into force.

The Irish result is also being closely watched in Britain where opposition leader David Cameron, tipped to win elections due by next June, has pledged to hold a referendum if he takes power and Lisbon has not yet been ratified.

Cameron, of the centre-right Conservatives, said that if a referendum is held, "I would ask the British people to vote No to that treaty".

But Sweden, the current holder of the rotating EU presidency, said the bloc wanted the final ratifications cleared up so that the treaty could enter into force by the end of the year.

British Prime Minister Gordon Brown said the Irish approval cleared the way for the bloc to move forward on key areas.

"We can now work together to focus on the issues that matter most to Europeans -- a sustained economic recovery, security, tackling global poverty, and action on climate change," he said.

The result was also welcomed in the Balkans, where EU membership candidates including Serbia had feared a second Irish No would torpedo their chances of ever joining the bloc.

The Yes vote "has opened doors to Europe that will have space for all European nations, including those from the western Balkans," Serbian Foreign Minister Vuk Jeremic told Beta news agency.

There have been suggestions in the European Parliament that former British premier Tony Blair could be given the job of EU president which would be created if the Lisbon Treaty is implemented.