Former Serbian president Milan Milutinovic voluntarily arrived in The Hague today to face trial on charges of war crimes during the 1999 Kosovo conflict.

"He's arrived at the tribunal. He's at the detention centre," a spokeswoman for the United Nations International Criminal Tribunal for former Yugoslavia said.

The Yugoslavian Foreign Ministry says the former ally of ousted Yugoslav leader Slobodan Milosevic, also on trial for Balkans conflicts including Kosovo, travelled to The Hague voluntarily.

"Having departed to The Hague by his own free will, Mr Milutinovic has fulfilled his duty as stipulated by the tribunal's statute and the Yugoslav law on cooperation with the international war crimes court," the Foreign Ministry said.

"He has also set an example to all other suspects."

Airport sources say a Yugoslavian Government plane carrying Milutinovic, whose five-year term as president of Serbia ended late last month, left Belgrade mid-morning.

Milutinovic, 60, was indicted in 1999 along with Milosevic and three other former senior officials for atrocities against ethnic Albanians in Kosovo, the southern province of Serbia now under UN rule.

UN chief prosecutor Carla del Ponte plans to meet Milutinovic soon.

Her spokeswoman declined further comment amid speculation he could be called to testify against Milosevic.

Prosecutors allege Milutinovic had at least formal control over Serb forces, who killed hundreds of ethnic Albanians and expelled hundreds of thousands from their homes.

But Milutinovic has said he does not feel responsible for the crimes he has been charged with, arguing that as Serbian president he had little real power.

Serbia is the dominant of the remaining two republics of Yugoslavia.

Milutinovic is expected to make his initial appearance before Hague judges later this week, when he will be invited to enter a plea to the charges against him.

Serbian officials worked to persuade Milutinovic to go voluntarily to the tribunal, arguing this should increase his chances of being released from custody pending trial.

The Belgrade authorities have given guarantees to the United Nations court that Milutinovic, who has undergone heart bypass surgery and complains of serious health problems, will attend his trial and cooperate fully with the tribunal.

Many others charged with war crimes following the bloody break-up of the former Yugoslavia remain at large, including two of the world's most wanted men - wartime Bosnian Serb leader Radovan Karadzic and his military commander Ratko Mladic.