* Klaus signs EU treaty
* Treaty seen entering force in December
* Focus on who will be first EU president
(Adds Klaus signing treaty, changes dateline)
By Jana Mlcochova
PRAGUE, Nov 3 (Reuters) - Czech President Vaclav Klaus signed the EU's Lisbon Treaty on Tuesday, bringing into force the EU's plan to overhaul its institutions and win a greater role on the world stage.
Klaus was the last EU leader to ratify the treaty and his signature means the bloc of nearly half a billion people can pick its first president and a more powerful foreign representative to speak for it in global affairs.
The treaty is aimed at giving the EU a bigger clout on the world scene and making it more flexible. This is intended to match the rise of emerging powers such as China.
The staunchly eurosceptic Czech president signed the pact after the country's Constitutional Court threw out a complaint against the treaty earlier on Tuesday.
"I had expected the court ruling and I respect it, although I fundamentally disagree with its content and justification," Klaus told reporters. "I signed the Lisbon Treaty today at 1500 (local time)," he said.
Klaus had been banned by law from signing the treaty until the court had ruled on a complaint by his allies in the Czech upper house of parliament, the Senate, who argued the treaty would erode national sovereignty.
ARGUMENTS REJECTED
The court rejected the arguments. "The judgment was unanimous; none of the judges filed a dissenting opinion to either the judgment or its reasoning," the court said in a written verdict.
The Czech parliament has approved the pact but Klaus long argued against it, saying it would turn the EU into a superstate with little democratic control.
"With the Lisbon Treaty taking effect, the Czech Republic will cease to be a sovereign state, despite the political opinion of the Constitutional Court," Klaus said.
Klaus had said he would raise no further obstacles to the document after EU leaders agreed last week to give the Czechs an opt-out from a rights charter attached to the treaty. Klaus says the exemption is necessary to avoid property claims by Germans expelled from Czechoslovakia after World War Two.
"It is now time surely that the European Union moves on, not talking about the institutional arrangements for years ahead, but talking about the vital problems that all of us face," British Prime Minister Gordon Brown said after the court ruling.
"And that is creating jobs, creating growth, building a safer and more secure environment and building greater security for European people."
After Klaus's signature, the treaty will come into force probably in December, turning attention to who will be the EU's first president.
EU leaders failed to agree at a summit last week in Brussels on who should take the job, whose powers are still somewhat unclear, and a special summit may be needed to reach a deal.
The chances of the once-favoured candidate, former British prime minister Tony Blair, seem doomed after he failed to win an endorsement from the European Socialists, his Labour Party's allies.
No front-runner has emerged, but possible contenders include Dutch Prime Minister Jan Peter Balkenende, former Finnish prime minister Paavo Lipponen and Luxembourg Prime Minister Jean-Claude Juncker. (Writing by Jan Lopatka, Editing by Andrew Roche/David Stamp)