A Nazi hunter criticized Serbian authorities on Wednesday for failing to seek the extradition of three men with suspected links to atrocities against Jews, Serbs and Gypsies during World War II. Efraim Zuroff, director of the Los Angeles-based Simon Wiesenthal Center's office in Israel, said Serbian authorities have done little to bring to justice Croats Ivo Rojnica and Milivoj Asner, and Hungarian Sandor Kepiro. "Sadly, we have heard a lot of nice words, but there was no concrete action" by Serb authorities to start the extradition procedure, Zuroff said after attending a commemoration for some 1,400 victims of the Nazi occupation in 1942 in Novi Sad, northern Serbia. Serbian officials refused to comment. In the past, Serbian authorities have said they would seek the extradition of the three men. Zuroff believes Serbia should request their extradition and bring them to trial here because some of their alleged crimes were committed in Serbia and the victims included Serbs. Kepiro, 93, who lives in Hungary, was identified last year by the Simon Wiesenthal Center as having been convicted twice in Hungarian courts, in 1944 and 1946, but never punished for his role in killings committed by Hungarian forces in Novi Sad after they entered the region in the wake of the Nazi occupation of Yugoslavia. Rojnica, 92, is believed to be hiding in Argentina, and Asner, 91, is thought to be living in Austria. Both men served in Croatia's World War II Nazi puppet regime and allegedly took part in the prosecution and death camp deportations of hundreds of Jews, Serbs and Gypsies, Zuroff said. In 2005, Croatia indicted Asner for crimes against humanity and war crimes, but Austrian authorities failed to arrest him, Zuroff said. In Vienna, a Justice Ministry spokesman reached by phone late Wednesday was unable to offer an immediate comment. Zuroff said that Argentina is ready to extradite Rojnica if a country formally requests his handover.