The former Hungarian military officer is still number one on the Simon Wiesenthal Center's latest list of most wanted Nazi war criminals.

He is accused of "complicity in war crimes" in a raid by Hungarian forces on the northern town of Novi Sad between January 21 and 23, 1942.

The exact charges will not be known until they are read out in court but prosecutors have said he will be charged with ordering the rounding up and execution of 36 people.

Over 1,200 civilians were murdered during the Novi Sad raid, according to the Wiesenthal Center.

The director of the Center Efraim Zuroff, Serbian war crimes prosecutor Vladimir Vukcevic and representatives of the Jewish community of Novi Sad will attend the opening of the trial, Vukcevic's office announced Wednesday.

Deemed by the Wiesenthal Center to be "the most important positive result" in bringing Nazi war criminals to justice over the past year, Kepiro's trial is scheduled to begin at the Budapest Municipal Court at 9:00 am (0700 GMT).

It is not clear how long the trial will last nor when a verdict can be expected.

Kepiro faced a first defeat Tuesday in court, where he had sued Zuroff for defamation.

The Budapest tribunal said Zuroff had the right to call him a war criminal based on a 1944 verdict where Kepiro was found guilty of war crimes.

Although he has admitted his presence at the Novi Sad raid, the fit 97-year-old has continued to claim his innocence.

"I haven't regretted anything, all I did was my duty!" he told Hungarian television ATV in October.

He has already been found guilty of the crimes in Novi Sad twice, in 1944 and then again in 1946, when the previous 10-year jail sentence was quashed.

Sentenced to 14 years, he avoided prison by fleeing to Argentina where he remained for half a century before returning to Budapest in 1996 where Zuroff tracked him down 10 years later.

With proceedings against another Nazi war criminal, Ukrainian-born John Demjanjuk, nearing their end in Germany, Thursday's trial could be one of the last of its kind, according to the chief Nazi hunter.

Nevertheless, "the indictment of Kepiro sends a powerful message that the passage of time does not diminish the guilt of the killers and that old age should not protect those who committed such heinous crimes," he said in a recent statement.

Justice will be done so that the people of Novi Sad and the families of the victims "can finally achieve a measure of closure, even if it is many years after the crimes," he added.

Kepiro's defence is provided by the National Legal Foundation, headed by Tamas Nagy Gaudi, a member of parliament of the Hungarian far-right Jobbik party.