A Belgian watchdog on anti-Semitism warned that the country’s public schools are becoming “Jew-free” zones because of harassment.

Joel Rubinfeld, president of the Belgian League Against Anti-Semitism, sounded the alarm in an interview for the weekly Le Vif/L’Express, which was published earlier this month and which revealed that the only Jewish student of the Emile Bockstael high school left it following harassment and threats that she received from classmates after she posted a picture of an Israeli flag on Facebook.

The school “has become Judenfrei, there are no more Jewish students there,” Rubinfeld said, using the German-language term that the Nazis applied to locales which had been rendered “free of Jews.”

According to the weekly, the school’s last Jewish pupil, identified only as Sarah, posted a picture of herself holding the Belgian flag alongside the Israeli one in summer. She received 288 abusive comments, including threats, on Facebook, also by classmates and other pupils she did not know.

In September, she began attending one of the Brussels region’s three major Jewish schools but the harassments continued. On Sept. 10, she received a photo of a former classmate performing a Nazi salute, telling her she is missed.

Her parents, who have four children, pulled her two older brothers, who are twins, from public schools for similar reasons, the weekly reported. Only their eldest born was able to matriculate in one.

Last week, Menachem Margolin, an Israel-born rabbi who runs European Jewish Association lobby group in Brussels, said certain members of European Jewish communities should be permitted to carry firearms to defend themselves against anti-Semitic attacks like the Jan. 7 slaying of four at a kosher supermarket near Paris.

On Monday, the CCOJB umbrella group of French-speaking Belgian Jews distanced itself from his call, saying in a statement that it “can only be explained by ignorance and panic.”