A European Jewish leader condemned antisemitism as a crime on Monday as Auschwitz survivors and Israeli officials marked 69 years since the liberation of the Nazi death camp.

The ceremony at the Auschwitz-Birkenau memorial took place on International Holocaust Remembrance Day, established by the United Nations in memory of 6 million Holocaust victims, including victims of Auschwitz, who were mostly Jews.

Some 20 survivors walked through the gate with the infamous “Arbeit macht frei” (work makes you free) sign and laid a wreath at the former camp’s Executions Wall, where inmates, mainly Polish resistance members, were shot dead. About 60 members of the Knesset, the Israeli legislature, joined the survivors for observances that included visits to the red-brick Auschwitz barracks, which house a collection of the victims’ belongings and hair, and a list of the names of some 4.2 million Jews who perished in the Holocaust. At the European parliament the European Jewish Congress president, Moshe Kantor, rejected free speech arguments over what he called the worldwide spread of antisemitism. Antisemitism is “not an opinion – it’s a crime”, he said.

In Italy, the president, Giorgio Napolitano, condemned as a “miserable provocation” threats against Rome’s Jewish community in recent days, including the delivery of packages containing pig heads to Rome’s main synagogue.

Napolitano said during Holocaust Memorial Day commemorations that recent insults made against the Jewish community were “comparable only to the repugnant material in those packages”.

Italian police also detained two men, ages 33 and 47, on suspicion of instigating racial hatred for antisemitic graffiti, including denial of the Holocaust, near the main judicial offices in Rome. Authorities say the men belong to different far-right groups. No arrests have been announced for the delivery of the pig heads.