Preliminary results from the autopsy conducted on Slobodan Milosevic indicate he died of a heart attack, sources at The Hague tribunal say.
Official results from the examination are expected within an hour.
The former Yugoslav President was found dead on Saturday in the Netherlands, where he was on trial for war crimes.
Mr Milosevic's lawyer said that the day before he died, he had complained he was being poisoned. Some have also suggested he may have killed himself.