BELGRADE, Yugoslavia -- Yugoslav President Vojislav Kostunica's party vowed to challenge the annulment of the Serbian presidential elections, claiming Monday that voter lists were inflated with the names of dead or nonexistent people.

The State Electoral Commission said Sunday's election will have to be repeated because the turnout was 45.5 percent, falling short of the required 50 percent minimum.

Kostunica, a moderate nationalist, won 67 percent of the vote in Sunday's election, more than twice as much as Miroljub Labus, a pro-Western deputy prime minister and an ally of Kostunica's main rival, Serbian Prime Minister Zoran Djindjic, according to the official count.

The commission said Serbs will have to vote again by Dec. 5, and the new election will be open to all candidates, including ultranationalist allies of former President Slobodan Milosevic, who is now on trial for war crimes.

Outdated and inflated

Kostunica's party, however, said late Monday it will officially protest the annulment of the elections, claiming that ballot lists were outdated and inflated with bogus names and the names of dead voters, thus increasing the official turnout requirement.

Party officials alleged that some 630,000 ghost voters were included in the figure of roughly 6.5 million eligible voters. The voting lists are known to be outdated from Milosevic's era, and it was not clear why Kostunica's camp did not protest before the elections were held.

"We have proof that the elections actually succeeded," said Nebojsa Bakarac, a leading member of Kostunica's Democratic Party of Serbia. He said the State Electoral Commission's decision to invalidate the elections is "unacceptable" because Sunday's election turnout was actually over 50 percent when adjusted for the alleged irregularities.

Earlier, Kostunica accused Djindjic of leading a "quiet boycott" of the elections "in order to stay in power" and pledged to topple his government.

During the elections, Kostunica vowed to topple Djindjic's government by calling new parliamentary elections next year if he becomes the Serbian president.

"I want to see the end of Djindjic's regime," Kostunica said. "The political crisis has deepened."

Djindjic's Democratic Party responded by saying Kostunica should resign as Yugoslav president because he failed to be elected in the dominant Yugoslav republic.

"Kostunica campaigned by declaring that the elections will represent a popular referendum on the fate of the Serbian government and Djindjic," the party said. "Since the referendum failed, if Kostunica has morals, he would resign."

Djindjic, as a prime minister, has more power than Kostunica. But Kostunica is far more popular because of his nationalist views, and his party is likely to get more votes in the eventual Serbian parliamentary elections that are likely to be held early next year. With a majority in the parliament, Kostunica's deputies can vote Djindjic's government out of power.