Serbia's latest attempt to elect a president has failed because of low voter turnout. It is the third attempt by Yugoslavia's main republic to elect a president. There is international concern that the political stalemate will stall crucial reforms.

An independent observer group monitoring the election said less than half of Serbia's six million eligible voters bothered to cast ballots despite appeals from the international community and even the Serbian Orthodox Church.

Because turnout was lower than the legally required 50 percent, the presidential ballot was to be declared invalid, as was the case during a runoff election in October.

Analysts suggested most voters stayed away this time because of the biting Balkan winter weather and public apathy stemming from perceived slow reforms and infighting among politicians.

It meant the third setback for Yugoslavia's President Vojislav Kostunica, who had hoped to trade his job for President of Serbia.

Mr. Kostunica's first attempt at the presidency came in a September election but he did not secure an absolute majority.

In October, he defeated a pro-market candidate backed by his rival Serbian Prime Minister Zoran Djindjic. But that run-off was declared invalid because of low turn-out.

On Sunday, Mr. Kostunica's main opponents were far right politicians who were reportedly involved in Serbian paramilitary organizations during the bloody Balkan wars of the 1990s.

Mr. Kostunica, a self-declared moderate nationalist, wants to become Serbia's President because his current position as Yugoslavia's head of state will disappear next year when, under a Western backed agreement, the country will cease to exist.

The new nation will be called the Union of Serbia and Montenegro, named after the last remaining Yugoslav republics. They will share defense and foreign policies, but otherwise lead independent lives.

There is international concern that the failure to elect Serbia's president will undermine this process and stall crucial reforms in a region still recovering from a decade of ethnic strife.

Serbia's parliament speaker will take over as caretaker-president if no successor can be found for the republic's current leader Milan Milutinovic.

Mr. Milutinovic's mandate expires in January and he is likely to be extradited to the United Nations War Crimes Tribunal in The Hague on charges of war crimes.