European Union leaders have agreed to give Ireland four months to come up with a plan to save the Lisbon Treaty.

The Lisbon Treaty, or the constitution, can only come into effect if all member states ratify it.

Jose Manuel Barroso is President of the EU Commission.

"I fully agree with *** that the vote was not against Europe. I made clear to the *** that commission will fully endorse its request that Ireland will be given more time to decide or to react and to come forward with proposals on the next steps."

Addressing a two-day summit in Brussels, Barroso also urged other EU nations to push ahead with ratifying the treaty.

The Lisbon Treaty was designed to underpin plans to further expand the bloc and create a potentially powerful new president and foreign chief to give the bloc a stronger world voice.

Irish voters rejected the reform treaty last Friday, raising concerns with the future of EU.

On Wednesday, Britain became the first country to ratify the treaty following the Irish "no" vote.

Also on the summit, European Union leaders approved Slovakia's bid to become a member of the euro currency zone. Slovakia will swap its koruna for the euro starting next year.