Europe's leaders are facing calls to abandon the controversial Lisbon Treaty after it was comprehensively rejected by Irish voters.

Governments across the EU pledged on Friday night to carry on with the process of implementing the treaty - the successor to the abandoned constitution - despite the Irish vote.

But with the treaty requiring the ratification of all 27 member states, there was no clear idea how they could move forward.

A subdued Irish prime minister Brian Cowen, who led the Yes campaign, made clear there would be no second referendum - as has happened in Ireland in the past - to try to reverse the result.

"That doesn't arise today because the people have just spoken," he said.

"My focus is on respecting the decision they have made. It is now my job to discuss with my European colleagues on how we will proceed in the light of this decision."

The result of the referendum - rejecting the treaty by a majority of 53.4% to 46.6% - was announced on Friday in Dublin Castle shortly after 5pm amid boisterous celebrations by No campaigners.

In Brussels, European Commission president Jose Manuel Barroso insisted that the treaty was not dead.

"I believe that we should not rush to conclusions," he said. "I believe that the treaty is alive and we should now try to find a solution."

French president Nicolas Sarkozy and German chancellor Angela Merkel issued a joint statement regretting the outcome and saying they remained convinced that the treaty's reforms were still needed to make the EU more effective.