Sandor Kepiro, 97, stands accused of murdering 36 people during a 1942 operation in the Yugoslav town of Novi Sad that claimed the lives of some 4,200 civilians.
But in court Mr Kepiro, who declared himself fit to stand trial, dismissed the charges.
“I am innocent and I am here on trumped-up charges,” he said. “This trial is a terrible thing. There is no basis to this, everything is based on lies.”
During the war Mr Kepiro, a gendarme captain in Hungary’s fascist forces, took part in the Novi Sad raid but has always maintained that while he helped arrest civilians he took no part on the bloodletting. Hundreds of Serbs, Jews and Roma were taken to the banks of the Danube and shot or thrown into the frozen river alive by Hungarian forces in apparent revenge for partisan attacks.
For his alleged role in the massacre Mr Kepiro at one time topped the Wiesenthal Center’s most-wanted Nazis list.
“It’s clear that this is one of the last major trials of Holocaust-era war criminal suspects,” Efraim Zuroff, chief Nazi hunter at the Wiesenthal Center.