Serbia has been urged to seek the extradition of three men wanted on suspicion of carrying out Nazi-era war crimes.
Efraim Zuroff of the Simon Wiesenthal Centre said that Serbia should take action over Peter Egner, who lives in the US; Milivoj Asner, a resident of Austria; and Sandor Kepiro of Hungary.
Mr Egner is wanted on suspicion of serving in a Nazi unit responsible for the deaths of 17,000 civilians, and Mr Asner is wanted in connection with alleged atrocities in Croatia. Mr Kepiro was convicted by Hungarian courts after the war but never punished for his alleged part in the deaths of hundreds of Jews and 400 Serbs in Yugoslavia.
"The issue in these cases is not finding the suspects, is not finding the evidence," Mr Zuroff said. "The problem has been the lack of political will by the countries in which these people reside.
"I'm referring primarily to Austria and Hungary, and not the United States where there are serious
efforts to bring Nazi war criminals to justice."