FACTBOX: Newly-independent Kosovo, still claimed by Serbia

(Reuters) - NATO troops and United Nations police clashed with ethnic Serbs in the northern Kosovo flashpoint town of Mitrovica on Monday, in the worst violence in the territory since the Albanian majority declared independence last month.

Here is a brief profile of Kosovo, an ethnic crossroads in the heart of the Balkans and the cause of NATO's first "humanitarian war" in 1999.

HISTORY

* Kosovo was first inhabited by Illyrian and Thracian tribes, ruled by the Romans then populated by Slavs in the 6th century. It became part of the Kingdom of Serbia in the 13th century, with a mixed population of Serbs, Albanians and Vlachs. The Nemanjic dynasty made it Serbia's spiritual centre, giving lands to the Orthodox Church and building many monasteries.

ETHNIC MAKEUP

* Many Serbs left in the 500 years after the Ottoman Empire defeated the Serbs at the 1389 Battle of Kosovo. The Albanians, converts to Islam, grew in number. Mutual expulsions and migrations to and from Albania in the early 20th century changed Kosovo's makeup. Today, 2 million Albanians form 90 percent of the population. Some 120,000 Serbs remain in Kosovo, just under half in the northern enclave and the rest in scattered villages protected by NATO.

POLITICS & ECONOMY

* Landlocked and poor apart from mineral deposits, Kosovo was an autonomous region of socialist Yugoslavia and had effective self-government in 1974. Ethnic tensions escalated in the 1980s as Yugoslavia began to crumble and the economy deteriorated. Populist Slobodan Milosevic used Serb nationalism as a springboard to power in 1989, restricting Albanian rights. Strikes and violence led to Belgrade declaring a state of emergency in 1990, sending in the army and police.

Unemployment currently stands at more than 50 percent and the territory's infrastructure is in urgent need of investment.

WAR

* Albanians demanded independence in renegade elections in 1992 which made pacifist leader Ibrahim Rugova president of a self-declared republic. The demand was ignored amid the wider Balkan wars and in the late 1990s ethnic Albanian Kosovo Liberation Army guerrillas launched an armed rebellion. Serb forces hit back so hard in 1998 that 100,000 Albanians fled to the hills and NATO powers warned Milosevic they would not tolerate another round of "ethnic cleansing" in the Balkans. Peace talks in France failed and in March 1999 NATO started bombing Serbia to force it to withdraw its forces. Some 800,000 Albanians fled or were expelled to Macedonia and Albania before Milosevic gave in 78 days later. As his forces pulled out, up to 200,000 Serbs and other ethnic minorities left as well.

LIMBO

* Kosovo came under United Nations administration, with NATO troops as peacekeepers, in June 1999. Spasms of ethnic violence, mostly by Albanians against Serbs, and organized crime tarnished its image with the West, but also made clear that the status quo was unsustainable. Two years of Serb-Albanian negotiations ended in failure in December 2006.

INDEPENDENCE

* Kosovo's ethnic Albanian leaders declared independence on Feb 17, swiftly winning recognition from the United States and major European Union countries. The EU is currently deploying a law and order mission to help the new state's progress. Serbia, with the help of its big-power ally Russia, has vowed to block Kosovo from getting a United Nations seat or joining major international financial organizations. It also wants to consolidate its control on Serb-dominated areas in the north of Kosovo, where police, civil servants, doctors and teachers still look to Belgrade as their government. Some analysts say this is leading to a de fact partition of the territory.