A neo-Nazi gesture, regarded by anti-Semitism researchers as a modern day Nazi salute, is rapidly spreading among anti-Semites in Europe and is being used by individuals to fly under the radar of strict anti-hate speech laws in parts of the continent.

The “quenellle” signal, extending one’s right hand toward the ground while the left hand grasps the shoulder, was devised by Dieudonné M’bala M’bala, a controversial French comedian who has been condemned in court several times for anti-Semitic remarks.

Over the past two months, the trend has gained popularity, prompting hundreds of Europeans to post online pictures of themselves performing the “heil” like salute. Many of the images were taken at sensitive sites such as in the Auschwitz concentration camp, the Anne Frank House and even the Western Wall.

In September, two French soldiers were punished for using the signal.

The phenomenon was addressed at length during a World Zionist Organization conference which took place earlier this week in New York, where key speakers warned of the rise in anti-Semitic activity throughout Europe.

“It is gaining more and more momentum, is very pervasive on the internet and social networks and is increasingly becoming a symbol of the Nazi regime, and does not look like a passing phenomenon,” Yaakov Hagouel, the Head of the World Zionist Organization’s Department for Combating Antisemitism and the conference organizer, told Hebrew website Ynet.

“The message is simple,” Hagouel said during the conference. “If we put down our head, they will strike our head. I call on the US Jewish community leaders, of all denominations, and on leaders worldwide to join us in this important struggle. We have no other nation, we must put an end to anti-Semitism.”

Earlier this week, two Turkish tourists were detained by guards at the Auschwitz museum for appearing to make a Nazi salute.

The tourists, a man and a woman, both 22, were taking pictures of each other in front of the gate to the former Nazi death camp under the iconic sign “Arbeit macht frei” — “Work makes you free” — and raised their right hands in the gesture of a Nazi salute.