Czech Republic President Vaclav Klaus speaks to reporters after signing the Lisbon Treaty in Prague on Tuesday. (Petr David Josek/Associated Press)

Czech President Vaclav Klaus has signed the EU reform treaty, completing the ratification process of a charter designed to transform Europe into a more unified and powerful global player.

Klaus, widely known as a Euro-skeptic, says he signed the Lisbon Treaty at the Prague Castle on Tuesday afternoon, just hours after his nation's Constitutional Court ruled that the document, which already has been ratified by all other EU nations, does not violate the country's constitution.

At the end of the ruling, whose reading took almost two hours, the constitutional court's chief judge, Pavel Rychetsky, said all formal obstacles for ratification "are removed." Klaus was the last obstacle to the full ratification of the treaty.

Klaus said he respects the court decision, even though he does not agree with it.

Before signing the charter, EU leaders agreed last week to Klaus's last-minute demand — an opt-out from the treaty's Charter of Fundamental Rights. The Czech leader asked for the option over worries of property claims by ethnic Germans stripped of their land and expelled after the Second World War.

Pavel Rychetsky, chairman of the Czech Constitutional Court, reads a decision regarding a complaint against the EU's Lisbon Treaty on Tuesday. (Petr Josek/Reuters)

European Commission president Jose Manuel Barroso said in Brussels he was "extremely pleased" with the outcome.

"Together with the commitments given by all member states to the Czech government at the European Council last week, I believe that no further unnecessary delays should prevent the entry into force of the Lisbon Treaty," Barroso said.

The Lisbon Treaty should now be in force by the end of the year, said Jerzy Buzek, president of the European Parliament.

The signing of the treaty will allow Europe to "move forward and deal with the main issues that the European Union must now face," said British Prime Minister Gordon Brown.

Failure of the treaty would have sent the EU into an unprecedented crisis. Negotiators say its reforms — creating a new EU president post, giving more power to the foreign policy chief and streamlining EU decision-making — are needed to make the EU more effective.