An autopsy on the former strongman, who was found dead in his cell on Saturday, was completed on Sunday. Milosevic had a history of heart problems.
The International Criminal Tribunal for the Former Yugoslavia (ICTY) requested the autopsy and toxicological analysis to establish the cause of death of the 64-year-old Milosevic.
Legal advisors to Milosevic, who was on trial in the Hague for war crimes, said that the former leader claimed in a letter written a day before his death and revealed to the media on Sunday, that he feared he was being poisoned.
“They would like to poison me. I’m seriously concerned and worried,” Zdenko Tomanovic quoted the letter, addressed to the Russian foreign ministry, as saying.
The claim was dismissed by chief war crimes prosecutor Carla Del Ponte who said suicide could not be ruled out.
Milosevic was being judged for genocide, war crimes and crimes against humanity over the 1990s Balkan wars that killed more than 200,000 people.
Ms Del Ponte told Italian newspaper La Repubblica: “He could have done it as a last act of defiance towards us. Perhaps he did commit suicide.”
She said it was “a great pity for justice” that Milosevic died before a verdict and said it was now more urgent than ever to arrest war crimes fugitives former Bosnian Serb army chief Ratko Mladic and the wartime political leader of the Bosnian Serbs, Radovan Karadzic.
Mr Tomanovic said the tribunal had given Milosevic a copy of a medical report which showed the presence in his bloodstream of a drug used to treat leprosy or tuberculosis.
He said that the blood analysis was done January 12 but Milosevic did not receive the report until last week. The tribunal press office could not be reached for comment, but the ICTY does not usually make medical reports public.
“In the letter, Milosevic stressed that the main reason that he was not allowed to go to Moscow for medical treatment (in December) was the existing fear by some that the careful examination by the Russian hospital would reveal that his health was being systematically destroyed,” Mr Tomanovic said.
He added: “Milosevic pointed out that during the last five years he had never used any such antibiotics, especially since he had never had leprosy or tuberculosis or any kind of infectious disease except for the flu.”
A Serbian pathologist was assisting and two Serbian observers were present at the autopsy, a tribunal spokesman said.
Rasim Ljajic, the human rights minister of Milosevic’s native Serbia-Montenegro, said: “We will meet again with the tribunal’s secretary during the day and after the autopsy results.”
Mr Ljajic, who is in charge of relations with the ICTY, added: “We will see if it will be possible to announce some results or, because of toxicology analysis, it would need at least 24 hours more to have more detailed results.”
Several Serbian newspapers openly accused the tribunal of killing Milosevic because the former Serb nationalist strongman was a thorn in its side.
Kurir, one of the Balkan state’s more lurid dailies, quoted a local doctor who had examined Milosevic in November.
He “was very ill while leaders of the New World Order wanted the former Serbian president to disappear because they were involved in the trial they couldn’t get out of,” the doctor, Vukasin Andric, was quoted as saying.
Mr Ljajic said: “We expect that Milosevic’s remains will be handed over to the family immediately after the autopsy, which means that the family can take him tomorrow (Monday).”