By Fatos Bytyci and Tatiana Darie
PRISTINA/BRUSSELS (Reuters) - Kosovo's government said on Wednesday it would re-run a watershed election in the ethnic Serb-dominated north, setting up a showdown with Serb hardliners opposed to EU-backed efforts to end Kosovo's de facto partition.
Sunday's election for councils and mayors was the first to be held across the entire territory of the mostly ethnic Albanian country, but was disrupted in the north, where up to 50,000 ethnic Serbs oppose Kosovo's 2008 secession from Serbia.
Masked men broke into polling stations on the Serb side of the ethnically divided town of Mitrovica, lobbing tear gas and smashing ballot boxes in a violent climax to days of open intimidation of would-be voters.
Kosovo's Central Election Commission decided on Wednesday to annul the election in north Mitrovica and hold a re-run on November 17, commission member Betim Gjoshi told Reuters.
The repeat election will pose a major security challenge to EU and Kosovo police, as well as NATO's 6,000-strong peacekeeping force in the country.
The Serb north has for years has been beyond the reach of Kosovo's authorities. Its participation in elections was central to a deal brokered by the EU in April to integrate the north, which Serbia agreed to support as a condition for the start of EU membership talks.
"SERBS MUST VOTE"
Serbian Prime Minister Ivica Dacic, meeting his Kosovo counterpart Hashim Thaci in Brussels, said it was vital that Serbs turned out to vote. Otherwise, he said, the few tiny pockets of Albanians living in the north could end up voting in their own candidate.
"If enough Serbs don't turn out, an Albanian will be picked for mayor," Dacic told a news conference. "Will there be conflict? There certainly will. Will there be clashes, even armed clashes? There will. Will that cause instability, and how can Serbia help? It can't," he said.
EU foreign policy chief Catherine Ashton, who brokered the accord and chaired Wednesday's talks, said Dacic and Thaci had agreed how to complete the electoral process, which should result in the creation of an association of Serb-majority municipalities with powers over areas such as economic development, health and education.
The police and courts will report to Pristina, however, ending years of limbo under a form of weak control from Belgrade. Kosovo Serb hardliners are fiercely opposed to integration.
Ashton said both sides would continue implementing the April agreement at an "accelerated pace", but her statement offered few details.
Kosovo broke away from Serbia in 1999, when NATO bombed for 11 weeks to halt the killing and expulsion of Albanian civilians by Serbian forces trying to crush a guerrilla insurgency. It declared independence from Belgrade in 2008.
(Writing by Matt Robinson; Editing by Kevin Liffey)