Kosovo is holding local elections as tension over the future status of the province continues.
Nato's 16,000-strong KFOR troops were bolstered by reinforcements ahead of the election, in which 1.5 million people are eligible to cast their vote.
Ethnic Albanians, supported by the United States, want independence but Serbia, backed by Russia, is vehemently opposed.
Serbia's government - which considers the province as the cradle of Serbian history, culture and religion - has advised the 100,000 or so Kosovo-Serbs to boycott the polls.
Split community
Security is especially tight in the town of Mitrovica, where the Ibar river splits Albanian and Serb communities.
The United Nations Interim Administration Mission in Kosovo (Unmik), the UN mission which has run Kosovo since the 1998-1999 war, is worried that Serbs might attempt to block polling stations in the divided northern town.
Unmik and the Organization for Security and Cooperation in Europe (OSCE), who are acting as election monitors, say they are ready to deploy "mobile polling stations" on the back of trucks if voters are prevented from casting ballots.
Kosovans are electing members to the 120-seat provincial assembly.
Parties representing independence are guaranteed 100 of those seats.
Ethnic Albanians account for about 90 per cent of Kosovo's two million population.
The rest of the seats are set aside for Serbs and other ethnic minorities including Roma, Slavic Muslims and Turks.
No majority
The polls, which come less than a month before the end of internationally mediated talks on Kosovo's future status, pit the opposition Democratic Party of Kosovo (PDK) against the ruling Democratic League of Kosovo (LDK).
According to the latest surveys, however, neither of the two main parties is expected to gain an outright majority.
The PDK is lead by Hashim Thaci, a former leader of the political wing of the separatist Kosovo Liberation Army (KLA), who fought Serbian forces in the 1998-1999 war.
Kosovo has been run by Unmik since mid-1999 when a Nato offensive drove out forces loyal to Slobodan Milosevic, the late Yugoslav president, over a brutal crackdown on the KLA and its civilian supporters.
The 530 German troops deployed as reinforcements on Friday will be supported by KFOR's 16,000-strong peacekeepers and around 9,000 policemen.
Around 150 observers from the Council of Europe and as many as 25,000 local monitors will watch for voting irregularities throughout the country.
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UN peacekeeper in Kosovo