Slobodan Praljak, a former commander of Bosnian Croat forces in Bosnia's 1992-95 war, appeared to take a drink moments after judges at the International Criminal Tribunal for the former Yugoslavia (ICTY) confirmed his 20-year sentence on appeal.
Praljak's case was one of the last to be decided at a tribunal for ethnic war crimes in the former Yugoslavia, the worst outbreak of violence in Europe since the end of World War II.
"Slobodan Praljak is not a war a criminal, I am rejecting the court ruling", he said, before raising his hand to his mouth and swallowing some liquid from a tiny glass bottle.
Slobodan Praljak was appealing his 20-year sentence for war crimes in the Bosnian civil war in the early 1990s.
The judge presiding over proceedings, Carmel Agius, immediately suspended the hearing and an ambulance was called for Praljak.
"In accordance with standard procedures, at the request of the ICTY, the Dutch authorities have initiated an independent investigation which is now ongoing".
It saw a total of 100,000 people killed and 2.2million displaced in the three-year war.
Croatia's state-run TV service later said he died in hospital in the Netherlands, a statement which was later confirmed by Prime Minister Andrej Plenković, who offered condolences to his family. "We voice dissatisfaction and regret about the verdict".
Preliminary tests show that a container from which a former Bosnian Croat military commander drank in a United Nations court contained a deadly chemical.
A spokesman for the tribunal, Nenad Golcevski, when asked by the Associated Press if he could confirm the death, said: "I have no information to share at this point".
The UN war tribunal found that despite his being informed of what was happening, Praljak failed to make serious efforts to stop soldiers from rounding up Muslims in Prozor in the summer of 1993. "We voice dissatisfaction and regret about the verdict", Plenkovic said on Wednesday.
Judge Agius declared the courtroom to be a crime scene as he restarted the hearing, though gave no further details. Please drop your comment!