A convicted war criminal from Croatia swallowed what he said was poison and died Wednesday after a United Nations court in the Netherlands upheld his 20-year sentence for committing crimes against humanity during the Bosnian war of the 1990s.

In a stunning end to the final case at the U.N.'s International Criminal Tribunal for the former Yugoslavia, former Croatian general Slobodan Praljak yelled, "I am not a war criminal!" in a courtroom and appeared to drink from a small bottle.

Medical staff at the tribunal in The Hague rushed to Praljak's side before he was taken to a local hospital, where he died, tribunal spokesman Nenad Golcevski told reporters at the court.

The courtroom where the dramatic scene unfolded was sealed off. Presiding Judge Carmel Agius said it was now a "crime scene" and that Dutch police could investigate. Police in The Hague declined to comment on the case.

Dutch police, an ambulance and a firetruck quickly arrived outside the court's headquarters and emergency service workers, some of them wearing helmets and with oxygen tanks on their backs, went into the court shortly after the incident.

Praljak and five other former Bosnian Croat officials were convicted as part of a criminal plan to carve out a Bosnian Croat mini-state inside Bosnia in the early 1990s. All had their guilty verdicts sustained by the U.N.'s war crimes court Wednesday.