PRISTINA (Kosovo) - Kosovars vote 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 of its declaration of sovereignty, a vow of independence that it has refused to acknowledge. That has deepened fears of the country's partition into a Serb north and an ethnic Albanian south, and a reverse of decades of efforts by the West to calm ethnic tensions in the region. In a sign of concern, police spokesman Besim Hoti said assailants in Kosovo's north fired overnight at a house used by NATO peacekeepers. No one was injured. Hoti said a letter threatening to attack those who could take part in the Kosovo poll was also found at the site. The incident comes just days after attackers ambushed and executed 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. Some 1.6 million voters are eligible to vote for 29 political parties, coalitions and citizens' initiatives to enter Kosovo's 120-seat parliament. Ten of those seats are reserved for minority Serbs, some of whom are running in the poll. Polls opened at 0600 GMT (1 a.m. EST) and close 1800 GMT (1 p.m. EST). Serbia's call for boycott further undermines the local government and their international overseers' attempts to bring Kosovo's north under Pristina's control. The lawless northern region has long evaded both international and Kosovo authority. Minority Serbs there are backed by Belgrade in their defiance. The region is patrolled by NATO peacekeepers and EU police, but is run as a fiefdom by local Serb leaders picked by Belgrade. In confidential cables published by the WikiLeaks website this week, US Ambassador to Kosovo, Christopher Dell warned partition would "re-open the Pandora's Box of ethnic conflict that defined the 1990s." The ruling Democratic Party of Kosovo of former rebel leader turned politician Hashim Thaci is tipped to have the edge in looking for coalition partners. The winner of the poll earns the right to form a government, according to Kosovo law. 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 US and most EU nations, have recognised Kosovo as a state, and a top UN court ruled earlier this year that Kosovo's secession did not violate international law. The move was expected to line up more support, but Serbia's diplomatic offensive arguing Kosovo's secession could inspire similar separatist moves around the world has discouraged countries from recognizing it, notably Russia and China.