The wartime commander of Bosnian Croat forces, Slobodan Praljak, died after he drank poison seconds after a United Nations judges turned down his appeal against a 20-year sentence for war crimes against Bosnian Muslims, Croatian state television reported.
The television quoted sources close to Praljak as saying he died in a hospital in The Hague.
The events took place in the final minutes of the court's last verdict. The International Criminal Tribunal for the former Yugoslavia (ICTY), established by the United Nations in 1993, shuts its doors next month when its mandate expires.
Slobodan Praljak, 72, tilted back his head and took a swing from a flask or glass as the judge read out the verdict.
"I just drank poison," he said. "I am not a war criminal. I oppose this conviction."
Praljak sat back down and slumped in his chair, a lawyer who was in the courtroom at the time said.
The presiding judge suspended the hearing and called for a doctor. An ambulance was at the building and paramedics went to the courtroom.