He was arrested in late January 2014 and has been kept in jail since. The first time he decided to embark on a hunger strike was when he demanded to be transferred from Pristina to a prison in Kosovska Mitrovica.
Ivanovic decided to go on a hunger strike now after an EULEX panel of judges on Thursday extended his detention until October 6.
His wife, Milena Popovic-Ivanovic, told Tanjug that her husband made the decision after reflecting on it for a long time, and added that he "simply cannot understand the injustice that is happening to him."
"He decided to start a hunger strike because he thinks it's the only way to draw attention to himself. His health is now good, he expects the doctors that will examine him, and he will be under medical supervision," Popovic-Ivanovic said.
His party has also confirmed the news, saying that Ivanovic wants "to point out to the inhumane and unjust stance EULEX has toward him."
A statement issued by the GI SDP said that Ivanovic made the decision "because this politically rigged trial has, after hearing 47 witnesses, arrived to a point when legal arguments no longer exist, instead there are only political ones, that we have been pointing out to since the beginning."
The statement added that "aware of the risks for his health, but also of the scorn shown for his rights, his family, friends and political associates support his decision."
Ivanovic is accused of committing war crimes against civilians in April 1999 and February 2000 when he allegedly incited to murder of several ethnic Albanians in Kosovska Mitrovica.
Four other Serbs are accused in this case. All five have pleaded not guilty.