The current Yugoslav President, Vojislav Kostunica, has won the initial stage of Serbia's presidential elections, the first poll since the fall of Slobodan Milosevic almost exactly two years ago.

Provisional results

Vojislav Kostunica - 31% Miroljub Labus - 28% Vojislav Seselj - 22%

He will face Yugoslav Deputy Prime Minister Miroljub Labus in a run-off vote in two weeks' time.

Ultra-nationalist Vojislav Seselj, who was backed by former President Slobodan Milosevic, finished third and is eliminated from the poll.

Mr Seselj had been endorsed by Mr Milosevic from The Hague, where the former leader is on trial on war crimes charges.

Low turn-out

After a low turn-out, estimated at 55%, Mr Labus said he was only 100,000 votes behind Mr Kostunica.

Rainy weather deterred some voters, but not Miroljub Labus

But as turnout is traditionally lower in the second round, there are now real fears that it will not reach the 50% threshold.

If that happens, the whole election will be invalid, plunging Serbia into a constitutional crisis, the BBC's Nick Thorpe reports from Belgrade.

Both leading candidates appealed to Serbians to come out in force in a fortnight's time.

"I expect those who did not vote now to come out and vote for me," said Mr Kostunica.

Nationalist camp

There was some concern at the strength of the ultra-nationalist vote, with Mr Seselj performing much better than expected.

Seselj did better than expected, but not well enough

Serbia's deputy prime minister, Nebojsa Covic, who supports Mr Kostunica, said: "The encouraging thing is that two pro-democracy candidates are entering the runoff.

"The discouraging thing is that some of the votes that helped oust Milosevic have now gone to Seselj."

Correspondents say that the combined vote for nationalist candidates, including the moderate nationalist Mr Kostunica, amounted to more than 60% of the vote.

However, Yugoslav Foreign Minister Goran Svilanovic, a backer of Mr Labus, also took heart from the fact that both leading candidates are reformers.

"The sum of both groups is still well over 50%, meaning that the country is still on a good course," he said.

Mr Kostunica will lose his job later this year when the Yugoslav Federation is dissolved into a much looser union between Serbia and the other republic, Montenegro.

Whoever wins will replace Milan Milutinovic, the last ally of Mr Milosevic still in power, who is indicted alongside him for alleged war crimes committed during the Kosovo war.

Mr Kostunica is the favourite to win the second round, is he is more likely than Mr Labus to benefit from the support of voters who chose one of the losing candidates on Sunday.