DUBLIN, Ireland - Ireland completed its ratification of the EU's Lisbon Treaty on Thursday, intensifying the pressure on the Czech Republic to overcome its objections and become the final member state to pass the treaty.

Irish President Mary McAleese announced she had signed a special legal instrument following a Yes vote in this month's referendum.

A statement from the president's office said she had "signed the Twenty-Eighth Amendment of the Constitution (Treaty of Lisbon) Bill 2009".

In a second referendum on October 2, Ireland voted by 67 per cent to 33 per cent to ratify the treaty, overturning a shock No vote in June 2008 which left the European Union in limbo.

Ireland is the only EU country constitutionally obliged to put the treaty - which is designed to streamline decision-making in the 27-nation bloc - to a referendum.

Irish Prime Minister Brian Cowen agreed to hold another poll after securing guarantees from its EU partners on the Catholic country's abortion ban, its military neutrality and its tax-setting rights.

But economic factors appear to have been the main factor in the minds of voters.

In this year's campaign, the government warned voters against rejecting the treaty at a time when Ireland needs help from its European partners to recover from a deep recession.

The treaty must be ratified by all member states, but Czech President Vaclav Klaus has insisted he will not drop his objections to the document despite mounting pressure from the rest of the bloc.

On Thursday, Czech Prime Minister Jan Fischer said his cabinet and Klaus were in talks about securing an opt-out from the treaty to prevent ethnic Germans forced out of the country after World War II from reclaiming their property.