THE HAGUE (AFP) –
The legality of Kosovo's secession from Serbia takes centre stage on Tuesday as the International Court of Justice opens hearings into Pristina's controversial decision to break away.

Serbia, Kosovo and 29 nations, including Russia and the United States, will unveil so far confidential arguments to The Hague-based ICJ, which will then hand down an opinion on whether Kosovo's actions were legal.

The hearings, to run until December 11, will address the question of the "accordance with international law of the unilateral declaration of independence by the provisional institutions of self-government of Kosovo."

Kosovo's decision to break away from Serbia on February 17, 2008, sparked an outcry from Belgrade, which still considers the ethnic Albanian majority southern territory to be an integral part of its history and culture.

Russia warned the move would set a dangerous precedent for separatists around the world, and its echoes resonated in Moscow's backing for two rebel regions in Georgia last August.

More than 60 nations have recognised Kosovo's statehood, including 22 of the 27 members of the European Union, which launched a massive justice and police mission to help chaperone the poverty-stricken region to independence.

Serbia, which has strong backing from its ally Russia, won agreement on October 8, 2008 from the United Nations General Assembly for Kosovo's actions to be heard by the court in the Netherlands.

Neither side has made public their planned arguments, but Belgrade does hope the hearings will provide it with enough leverage to force open negotiations once again with Kosovo on its status.

Frustration over that long and apparently unreconcilable process led the United States and most of the European Union to commit to backing Kosovo, which is home to some two million people, 90 percent of them of Albanian origin.

Serbia and others who refuse to recognise Kosovo are likely to underline to the judges the fact that international law does not allow a country's borders to be modified, as Pristina did by breaking away, said Steven Blockmans, from the Asser Institute, which specialises in international law.

Kosovo's suppoers are likely to argue that "people in Kosovo were so oppressed by the Serbian government -- which did not respect their right for self determination, which did not respect their human rights -- that you can not have this situation of internal colonisation," he said.

Until last year, Kosovo had been under UN supervision, following a NATO bombing campaign in 1999 against former Serb strongman Slobodan Milosevic to stop his crackdown on ethnic Albanian separatists.

The ICJ was set up to rule on disputes between sovereign states, but can also be asked by the UN to give an advisory opinion on legal questions.

It has issued 25 such advisory opinions since it started work in April 1946, but such opinions are not binding.