PARIS — The Hungarian authorities said Wednesday that they had placed under house arrest a 97-year-old man who is accused of overseeing a Jewish ghetto at the end of World War II, torturing prisoners and helping to organize the deportation of up to 12,000 people to Nazi concentration camps.

The investigation was ordered after Efraim Zuroff, who heads the Simon Wiesenthal Center in Jerusalem, reported that the man, Laszlo Csatary, was living in the Hungarian capital last September.

“None of these cases exist in a judicial vacuum,” Mr. Zuroff said. “They often have a very strong political dimension. Without the will to bring such criminals to justice there is no way to hold them accountable.”

At a press conference Wednesday, Tibor Ibolya, the chief prosecutor of Budapest, said the suspect denied wrongdoing, but said that he had been following orders, the Hungarian state news agency MTI reported.

Mr. Ibolya said Efraim Zuroff’s recent comments in the media, including criticism of the fact that Mr. Csatary had not been charged, prejudiced the outcome of the investigation.

He said at the news conference that Mr. Csatary, who is in good physical and mental health despite his age, had cooperated with the authorities.

Mr. Csatary to this day harbored anti-Semitic feelings, Mr. Ibolya said, citing the detainee’s comments.

“I can say his statement and his sentences show how he relates to people belonging to a certain religion,” Mr. Ibolya said. “He doesn’t relate to certain fellow human beings in what we would consider to be a normal way. If you think about 1944 and why he is a suspect, I think it’s clear what I mean,” he was quoted as saying by Bloomberg News.

Later, a Budapest court ordered that Mr. Csatary be placed under house arrest for 30 days.

The prosecutor’s office declined to comment on the course of further investigations, the circumstances of Mr. Csatary’s detention or details of his questioning on Wednesday.

The prosecutor’s office said in a statement that Mr. Csatary, identified only by his initials, had supervised a ghetto in the city of Kassa, today Kosice, Slovakia, in 1944, where he “regularly whipped and abused prisoners, without a particular reason, regardless of their sex, age or state of health.”

nytimes.com