Kosovars are voting Sunday in the first general poll since the country's declaration of independence from Serbia in 2008, a critical election already marred by ethnic tension that many fear will split the world's newest country.

Serbia has called for Kosovo's Serb minority to boycott the vote in protest at its declaration of independence that Belgrade has refused to acknowledge. The boycott call has deepened fears the country could split into a Serb north and an ethnic Albanian south, a reverse of decades of efforts by the West to calm ethnic tensions in the region.

The move is likely to weaken Pristina's claim over the territory in upcoming EU-brokered talks with Serbia on resolving the long-standing dispute. The region is patrolled by NATO peacekeepers and EU police, but is run as a fiefdom by local Serb leaders picked by Belgrade.

Some 1.6 million voters are eligible to vote and 29 political parties, coalitions and citizens' initiatives are seeking to enter Kosovo's 120-seat parliament. Ten of the seats are reserved for minority Serbs, some of whom are running in the poll. Turnout reached 34 per cent over three hours before polls closed at 1800 GMT, top elections officials said.

But minorities in Kosovo's north were discouraged from taking part in the vote after violent attacks aimed at intimidating potential voters. Officials said polling stations in Kosovo's north closed three hours ahead of time for security reasons.

On Sunday, a clandestine Serb group calling itself White Eagles acknowledged responsibility for the slaying of a Bosniak leader loyal to Kosovo's ethnic Albanian-dominated institutions. He had been involved in organizing the weekend poll in Mitrovica, a town divided between Albanians and Serbs since the end of the 1999 war.

The group warned in a letter obtained by The Associated Press it would "not allow Albanian elections to be held" in Kosovo's north and said it would "make life worse" for all those who take part. The group also threatened NATO peacekeepers and EU police, treated as collaborators of ethnic Albanians.

The letter was left after shots were fired at a house used by NATO peacekeepers in the Serb-run north, police said.

In confidential cables published by the WikiLeaks website this week, U.S. Ambassador to Kosovo Christopher Dell warned partition would "reopen the Pandora's Box of ethnic conflict that defined the 1990s."

Kosovo's Prime Minister Hashim Thaci said he hoped the vote would not be disrupted and urged everyone to take part.

"I hope everything goes OK," Thaci told The Associated Press, minutes before casting his ballot in the capital Pristina. "We will have free and democratic elections with the participation of all communities and build a government as soon as possible," Thaci said, flanked by his wife and 11-year-old son.

No party is expected to gain enough seats to rule alone, but the winner of the poll earns the right to try to form a coalition government, according to Kosovo law. The ruling Democratic Party of Kosovo of former rebel leader turned politician Thaci is tipped to have the edge.

Thaci was in charge of a coalition government that declared Kosovo independent from Serbia in 2008. Since then, Kosovo has struggled to establish itself as an independent country.

So far 70 countries, including the U.S. and most EU nations, have recognized Kosovo as a state.

Despite a top U.N court ruling earlier this year that Kosovo's secession did not violate international law -- a move expected to line up more recognition -- Serbia's diplomatic offensive arguing Kosovo's secession could inspire similar separatist moves around the world has discouraged some countries from recognizing it, notably Russia and China.