A former Croatian Serb leader who was a key witness in the trial of Slobodan Milosevic has killed himself.

Milan Babic committed suicide in his prison cell at the UN War Crimes Tribunal in the Hague.

The 50 year old was serving a 13 year sentence for crimes including murder, deportation and unlawful imprisonment of non-Serb civilians.

In 2002 Babic testified against Milosevic, and was being held in The Netherlands in order to give evidence against Milan Martic, another Croatian Serb.

In 1991 Babic was president of the self-declared breakaway Serb republic of Krajina - an area that covered about a third of Croatian territory.

At his trial in 2004 he said he came before the tribunal with a "deep sense of shame" for being part of the plan to remove the Croat and non-Serb population from Krajina.

The indictment against him said that the 80,000 Croats and Muslims in Krajina in 1991 were "forcibly removed, deported or killed" within a year.

His relations with Milosevic began to deteriorate over the course of the Croatian war as he aimed to create a state of western Serbia that would rival Belgrade.

It was thought that he feared retribution for testifying againt Milosevic, and until being taken back to the Hague recently he was serving his sentence at a secret location.

PHOTO CAPTION

Milan Babic. (AP PHOTO)