(CNN) -- Former Bosnian Serb army chief Ratko Mladic refused to testify Tuesday at the genocide trial of former Bosnian Serb leader Radovan Karadzic in the Netherlands and denounced the U.N.-backed court as "satanic."
Both men are on trial at the International Criminal Tribunal for the former Yugoslavia, or ICTY, for their role in the conflict that followed the breakup of the former Yugoslavia two decades ago.
But Mladic said he does not recognize the court in The Hague and rejects it as satanic. "It is not a court of justice, and it is trying us because we are Serbs and are trying to protect our people from you," he said.
The former army chief, who was arrested in May 2011 after a decade on the run, is being tried separately from his former ally, Karadzic, but was called Tuesday as a defense witness in latter's trial.
Mladic agreed to answer only the first of six questions put to him -- on the positions held during his military career -- arguing that his testimony could harm his own case.
Karadzic faces two counts of genocide, among other charges, one of which relates to the massacre of nearly 8,000 Muslim men and boys in the Bosnian town of Srebrenica in July 1995.
The second question put to Mladic by Karadzic's defense was, "Did you ever inform me, orally or in writing, that prisoners in Srebrenica would be, were being, or had been executed?"
The next was, "Did we have any agreement or understanding that the citizens of Sarajevo should be subjected to terror by shelling and sniping?"
Mladic was also asked about the reasons for the shelling and sniping in Sarajevo, and what he had told Karadzic.
More than 10,000 people, most of them civilians, died in the lengthy siege of Sarajevo, the Bosnian capital, by Bosnian Serb forces that pounded the city every day from higher ground.
Mladic was also asked if he and Karadzic had any agreement "to expel Muslims or Croats residing in Serb-controlled areas" -- a question related to the second genocide charge faced by Karadzic.
The court proceedings are now in recess, the ICTY said.
There was already an early break in proceedings after Mladic asked to be brought his dentures before he answered questions, said ICTY spokeswoman Magdalena Spalinska.
Karadzic was captured in 2008 after more than 13 years of hiding in plain sight in Belgrade. He had adopted an elaborate disguise that included long hair and a full beard, and was practicing alternative medicine in the Serbian capital.
His trial started in 2009, and the prosecution rested its case in May 2012. The defense case began in October of that year.
Mladic is accused of genocide, crimes against humanity and war crimes in a trial that began in 2011.
Both men would face life in prison if convicted. The court cannot impose the death penalty.
The ICTY is still prosecuting a number of cases of alleged war crimes committed during the conflicts in the Balkans in the 1990s.
The Srebrenica massacre became an emblem of the dissolution of Yugoslavia -- once a multiethnic state of Serbs, Croats, Muslims and others -- into six countries during a bloody and brutal conflict.
Other defendants at the court include Croatian Serb rebel leader Goran Hadzic, accused of crimes against humanity and war crimes; and Vojislav Seselj, a Serb nationalist politician who faces charges of crimes against humanity and war crimes.
The tribunal says "the most significant number" of its cases have dealt with alleged crimes by Serbians or Bosnian Serbs.
But there have been convictions for crimes against Serbs by others, including Croats, Bosnian Muslims and Kosovo Albanians.
CNN's Khushbu Shah contributed to this report.