UN war crimes judges have ordered an indefinite halt to the trial of Croatian Serb rebel leader Goran Hadzic who is suffering from brain cancer, according to a ruling released Tuesday.

In a majority decision, the judges at the International Criminal Tribunal for the former Yugoslavia (ICTY) found that Hadzic "is currently unfit to stand trial".

Hadzic, 57, was the ICTY's final suspect, wanted on 14 war crimes and crimes against humanity charges for his role in the 1991-95 war in Croatia, including the murder of civilians taken from Vukovar hospital in 1991 in one of the conflict's darkest episodes.

He is also charged with responsibility for the massacre of Croat civilians who were forced to walk into a minefield in the Croatian town of Lovas in October 1991 -- one of the first crimes of the long, bloody conflict.

In its judgement made on March 24 but only released Tuesday after being redacted, the court said reports from UN medical officers had shown "a recent and marked deterioration in Hadzic's ability to communicate".

Various medical reports had led the court to find Hadzic was "no longer able to effectively exercise his fair trial rights, even with the assistance of counsel".

Rather than drop the proceedings, the judges ordered that they be halted "indefinitely".

Hadzic was arrested in Serbia in 2011 after seven years on the run, after the initial indictment was issued against him in 2004. He was transferred to the UN tribunal's detention unit where his trial opened in October 2012.

He was diagnosed with terminal brain cancer in November 2014, with doctors saying he had at best another two years to live. He was released provisionally in April 2015 to be allowed to travel to northern Serbia for treatment.

Hadzic wanted to create a Serb-dominated state after the splintering of the former Yugoslavia in 1991 following the collapse of communism.