In his oath of office, Tadic, 50, will "solemnly swear that I will devote all my efforts to preserve the sovereignty and territorial integrity of the Republic of Serbia, including Kosovo and Metohija as its constituent part".

But on Sunday, Serbia already faces dismemberment with the loss of Kosovo, the mountain-ringed province steeped in Serb myth but now home to 2 million Albanians, a 90 percent majority.

Nationalist Prime Minister Vojislav Kostunica, who has eclipsed pro-Western Tadic to become undisputed champion of Serbia's unity, has told Serbs that Kosovo's breakaway is "about to become a reality" he can't stop but will never accept.

The West plans to recognise Kosovo because it says Serbia relinquished the moral right to rule its people with the brutality it used against them in 1998-99 under the late Slobodan Milosevic, and because there is no hope of compromise.

Serbia and its ally Russia insist that the legal rights of sovereignty and territorial integrity are paramount over an ethnic minority's demands for self-determination.

Serbia has offered autonomy to Kosovo Albanians within Serb borders, but no role as full citizens. Belgrade's proposal is for separate lives, a formula the West believes is unsustainable in the long term.

Kosovo has already been under United Nations administration and NATO protection for nearly 9 years.

"OURS TO THE END"

Serbian Foreign Minister Vuk Jeremic told the United Nations on Thursday Serbia would not use military force, but "all diplomatic, political, and economic measures ... to impede and reverse this direct and unprovoked attack on our sovereignty."

Russia's U.N. ambassador Vitaly Churkin argued "Milosevic has been gone for 10 years". But Western critics say Serbia has not done enough to repair the wreckage his policies inflicted on ethnic harmony in the former Yugoslav federation.

Hardline nationalism is still a powerful force in Serbia. No mainstream politician has taken the risk of conceding that Kosovo may have been effectively lost 9 years ago when thousands of Albanian civilians were killed by Serb forces.

Nationalists have called for protests in Belgrade next week against the United States and European Union. Tens of thousands are expected to participate. Ambassadors were preparing to withdraw from EU embassies for consultations at home.

Russia warns that the West is letting a dangerous genie out of the bottle by supporting Kosovo's secession without U.N. approval. It says separatist movements the world over will take note that they too may be able to seize independence.

Russia said on Friday international recognition of Kosovo would influence its policy towards Georgia's breakaway regions of Abkhazia and South Ossetia, but did not say if it would recognise them.

Western powers argue Kosovo is not a precedent but a unique case, brought about by the savagery of an autocracy towards an ethnic minority.

Ethnic Albanians in the borderlands of Macedonia, Montenegro and south Serbia say they look forward to Kosovo's independence and discount concern that they too will attempt to secede to create a "Greater Albania" in the Balkans.

But there are fears that the shockwaves of Yugoslavia's long, slow and bloody collapse have not subsided yet. In Bosnia, Serbs who won an autonomous half of the country in the Dayton peace deal that ended the 1992-95 war say they too will demand to secede if Kosovo gets its way.