The trial of a 97-year-old Hungarian, Sandor Kepiro, for alleged Nazi-era war crimes was temporarily halted on Tuesday over concerns that the defendant was incapable of following the court proceedings, DPA reported.
Prosecutor Zsolt Falvai called for Kepiro to undergo a psychiatric review, citing "concerns raised" by his apparent inability to understand what was being said in the courtroom, the state news agency MTI reported.
Kepiro's defence lawyer said that his client suffered only from partial deafness, and asked for a professional medical evaluation of the defendant's ability to hear.
However, in reply to a question by presiding judge Bela Varga, Kepiro said his "mind could not grasp" what was being said in the courtroom.
Kepiro is accused of taking part, as the leader of an armed police unit, in the slaughter in January 1942 of mainly Serbian and Jewish civilians in what is now northern Serbia.
The event claimed over 1,000 lives and became known as the Novi Sad massacre, part of a series of reprisal killings.
During the Second World War, Hungary was one of the Axis powers allied to Nazi Germany.
Kepiro's trial, which opened the previous week, is expected to be one of the last attempts to bring to justice an alleged perpetrator of Nazi-era war crimes.