The UN war crimes tribunal in The Hague said in a statement that Babic was found dead on March 5 in his cell at a detention center in Scheveningen.
The tribunal said his death had been ruled to be suicide.
Babic was serving a 13-year sentence for persecuting non-Serb civilians. He was considered a key ally of former Yugoslav President Slobodan Milosevic.
A judge at the tribunal has ordered an inquiry into Babic's death.
Milosevic On Trial
For an archive of RFE/RL's coverage of the trial of former Yugoslav President Slobodan Milosevic, click here.
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