The ICTY trial chamber is expected to deliver a verdict in the Margetic case on 7 February.
The presence of the accused at the announcement of the verdict would be in the interest of justice, the trial chamber said in a decision on Friday.
Margetic held a news conference in Zagreb on Friday afternoon to state that he intended "to come back from The Hague either as a free man or be transferred back in a coffin".
He said that he was told by an unnamed source at the ICTY Registrar's Office that he would get a prison term for having revealed a list of 102 protected witnesses who testified at the trial of a former Bosnian Croat military leader, General Tihomir Blaskic.
Margetic appealed to journalists not to allow his imprisonment, as "this time it may be Margetic and tomorrow some other Croatian journalist".
Margetic, who had been on a 33-day hunger strike while he was treated in a prison hospital in Zagreb last year, said that he started another hunger strike today.
Before going on strike, he went to hospital for a medical check-up this morning and was told that he would be able to stay on a hunger strike for no longer than 10 days.
He said he was ready to die in case of imprisonment.
Margetic, who is perceived as a controversial journalist with rightist views, accused the incumbent government led by Prime Minister Ivo Sanader of "sending him to The Hague" and added that experts and the Sanader cabinet should be held responsible for his possible death.