By Nick Hawton BBC correspondent in Belgrade

Less than half the electorate turned out to vote in Sunday's election. It's the third time in just over a year that the vote has failed because not enough people cast ballots.

Prime Minister Zoran Zivkovic insists there is no crisis

When it became clear that yet another presidential election had failed, the Serbian Prime Minister, Zoran Zivkovic, quickly appeared before a news conference in Belgrade and insisted the republic's institutions were not entering a period of crisis.

But few doubt they're entering a period of uncertainty.

Many reasons have been given for the low turnout: an opposition boycott of the poll; electoral rules, which basically prevent Serbs living abroad from voting; candidates who just did not appeal.

All have played a part.

But underlying all is a deep disillusionment with politics.

The fall of the former Yugoslav president, Slobodan Milosevic, in October 2000 raised the hopes of many.

Soul-searching

But the grand coalition of democratically orientated parties, which came together to defeat him, has gradually split and crumbled.

In recent months that process has been accelerated by a series of high-profile scandals. The previous optimism of many ordinary Serbs has been shattered.

And that has enabled parties like the strong nationalist Serbian Radicals, which gained the most votes in this election, to capitalise.