Budapest prosecutors said in a statement Monday that they were investigating a case based on information received from the Simon Wiesenthal Center's Jerusalem office, but did not name the suspect.
The centre has told prosecutors that a Budapest resident named Laszlo Csatary is believed to be the former police chief in the Slovak city of Kosice in 1941, who played a "key role" in sending more than 300 Jews to their deaths in Ukraine.
Csatary, who the centre says would now be 97 years old, is also suspected of helping to organize the 1944 deportation of some 15,700 Jews to Auschwitz.
A man bearing a similar name lived in Canada as a citizen until August 1997, according to Canadian government officials.
A statement from Citizenship and Immigration Canada said Ladislaus Csatary had his Canadian citizenship revoked for resorting to "fraud and misrepresentation" to enter the country.
"It was alleged that when applying to immigrate to Canada, Mr. Csatary had provided false information about his nationality, and had failed to provide information concerning his collaboration with Nazi occupation forces while serving with the Royal Hungarian Police and, while in this service, his participation in the internment and deportation to concentration camps of thousands of Hungarian Jews," said the statement emailed to The Canadian Press.
Csatary reportedly obtained his citizenship in 1955, six years after emigrating to Nova Scotia from Europe. He reportedly spent at least some of his time in Canada working as an art dealer in Montreal. The statement said Ladislaus Csatary left Canada voluntarily to avoid deportation.
A spokeswoman with the Ministry of Justice declined to comment on whether there was a connection between Ladislaus Csatary and the man under investigation in Budapest.
In April, a man named Ladislaus Csizsik-Csatary was placed at the top of the Wiesenthal Center's list of its most wanted war crimes suspects. Csizsik-Csatary had been convicted in absentia for war crimes in Hungary in 1948 and sentenced to death.
The Simon Wiesenthal Center believes Ladislaus Csizsik-Csatary is indeed former Canadian Ladislaus Csatary.
Efraim Zuroff, the centre's self-described chief Nazi hunter, said a paid informant had provided the information last September that Csatary was living in Hungary and apparently had done so since leaving Canada.
"His information has been super-reliable," although he will not receive any money unless Csizsik-Csatary is convicted and punished, Zuroff said Monday in a telephone interview with The Associated Press.
He declined to name the informant, or say how much he would receive.
Word of the probe touched off domestic and international calls for Csatary to face trial for war crimes.
A group of students held a protest Monday at an apartment building in Budapest where Csatary is thought to have lived until recently, while the opposition Socialist party called on the country's chief prosecutor to indict him.
Some 40 protesters gathered at the Budapest apartment building Monday, among them members of the European Union of Jewish Students. They formed a line by binding their wrists to each other with tape and shouted "Never again!" One of the protesters put a crossed out swastika sticker on the door of the second floor apartment where Csatary is thought to have lived.
"We came here because we want the Hungarian organs of justice to start a process against this war criminal," said Krisztian Szilberhar, a young lawyer who participated in the protest. "He is responsible for the death of many innocent people."
Considering Csatary's age, "it would be enough justice if they declared him guilty and he had to continue to live here," Szilberhar added.
Deborah Abisror of the European Union of Jewish Students said she was disappointed that they were not able to find Csatary.
"He's not here, obviously," she said. "He shouldn't move anymore. He just should confront what he did. Maybe just to say sorry."
_ By Michelle McQuigge in Toronto. With Files from the Associated Press.