Greece's top Jewish body said a memorial to thousands of Jews killed in the Holocaust had been vandalised in Thessaloniki, the second such incident in as many weeks.
A mural commemorating the deportation of the Jews of Thessaloniki, Greece's second city, to the Nazi camps of Auschwitz-Birkenau had been daubed with swastikas and fascist symbols, it said.
"Vandal anti-Semites roam freely and stain undisturbed any attempt to preserve Holocaust memory in Thessaloniki," the Central Board of Jewish Communities in Greece (KIS) said in a statement.
Last month, a swastika and a fascist symbol were also sprayed on a monument dedicated to the Jewish cemetery of Thessaloniki, one of the oldest in Europe, which was destroyed in 1942 when Nazi Germany occupied Greece.
There have been no arrests.
"Once again we call upon the authorities to take all necessary measures in order to arrest the perpetrators and bring them to justice," KIS said.
"Statements of condemnation are not enough! It is unacceptable that those responsible for the vandalism of memory remain at large," it added.
Jewish memorials and cemeteries are often vandalised in Greece, where anti-Semitism is rampant.
The conservative government of Prime Minister Kyriakos Mitsotakis includes three ministers who were formerly senior members of a Greek far-right party.
There are 6,000 Jews in Greece now. An estimated 60,000 Greek Jews perished in the Holocaust — around 83 percent of the pre-war community.
