Former Croatian Serb rebel leader Goran Hadzic arrived in Serbia late on April 15 after the UN's International Criminal Tribunal for the former Yugoslavia (ICTY) ordered his provisional release.
The Hague-based ICTY has agreed to release Hadzic, who has been diagnosed with terminal brain cancer, until next month.
He will remain in Novi Sad, where he will undergo treatment.
Hadzic, 56, is the last suspect charged by the ICTY with war crimes during the Balkan wars to be prosecuted.
Hadzic, president of the self-proclaimed Republic of Serbian Krajina from 1992-94, faces 14 counts of war crimes and crimes against humanity for his role in the 1991-95 war in Croatia.
He pleaded not guilty.
Hadzic's trial has been suspended since October 2014 as he is not able to take part because of the side effects of his treatment.
Doctors saying he has up to two years to live.