Members of the upper house approved the treaty by 54 votes to 20.

However, Czech ratification still depends on the signature of President Vaclav Klaus, an outspoken eurosceptic and opponent of the treaty.

Following the Senate approval, President Klaus said the senators had ‘turned their backs on the Czech Republic’s interests.’

European Commission President José Manuel Barroso expressed his delight at the Senate approval in a statement released following the vote. He said: ‘I am very happy at the approval today of the Lisbon Treaty by the Czech senate, which completes the parliamentary process of ratification in the Czech Republic.’

The onus is now on Ireland to complete ratification, with a second referendum due to take place by November. Irish voters rejected the treaty in a referendum in June 2008.

Ratification of the treaty has also been delayed in Germany and Poland. A legal challenge has delayed German ratification, although parliament has approved it. In Poland, President Lech Kazynski, also a eurosceptic, has refused to sign the treaty until after the Irish vote. As with Germany, the Polish parliament has passed the treaty.

The treaty cannot take effect until all 27 members ratify it.

The Lisbon Treaty aims to implement institutional reforms and streamline decision-making processes to reflect the EU’s enlargement from 15 to 27 states in the past five years.