Irish politicians have been reduced to crediting Brussels for everything from economic success to peace in Ulster in an attempt to win Thursday's referendum on the EU constitution.

European Union leaders stepped up appeals to Irish voters to say 'Yes' to the Lisbon Treaty in a vote that could seal the fate of seven years of reform efforts.

The treaty paves the way for an EU president and foreign minister and abolishes dozens of national vetoes on proposals.

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Critics say it is effectively the same document as the controversial European Constitution which was rejected by France and Holland three years ago.

The final two opinion polls in the only EU state to hold a popular vote alarmed EU officials and revived memories of the crisis after French and Dutch voters threw out the draft EU constitution in 2005.

One survey showed the 'No' camp with a five-point lead for the first time. Another put the 'Yes' camp slightly in front with rejectionists gaining ground. Both suggested turnout and undecided voters will be crucial.

Both sides made their final appeals to voters yesterday after agreeing not to campaign on polling day.

'I believe that the people at the end of the day recognise that this Irish economy is hard-wired into the European economy,' said the country's new prime minister, Brian Cowen, insisting that EU money had driven the republic's transformation in the past decade.

And he warned that future generations would not thank voters if they derailed the European project 'which has been the greatest force for peace and prosperity in our history and the history of Europe'.

Luxembourg Prime Minister Jean-Claude Juncker, chairman of the euro zone finance ministers, said he hoped the Irish would endorse the treaty but acknowledged it was virtually incomprehensible to citizens.

He said: 'European matters are very complicated for citizens. We speak a language that is not understandable for the people.'

Irish analysts have said appeals from European Parliament groups could be counterproductive in a fiercely independent electorate.

'The political elite are prepared say anything to ensure this pet project gets through,' said Neil O'Brien, of the think-tank Open Europe.

'The experience in Ireland shows that the people are far more sceptical of the project than their leaders. That's why there is only one referendum being held.'

Most of the country's political parties, the powerful farming lobby and the congress of trade unions support the treaty.

But all 27 EU member states have to ratify it for it to come into force. This means Ireland - with less than 1 per cent of the EU's 490million citizens - could scupper plans for greater integration.