The incident took place Saturday when around 300 people gathered at La Almudena cemetery, with footage on social media showing several people in the crowd repeatedly giving the Nazi salute.

The rally, which was also attended by a Catholic priest, was a commemoration of the so-called “Blue Division”, a unit of Spanish military volunteers that fought for the Nazis during World War II.

At the cemetery, they laid flowers in front of the memorial to the fallen Blue Division soldiers.

During the rally, a young woman gave an inflammatory speech echoing rhetoric from the 1930s.   

The region's prosecutors confirmed they had opened “criminal investigation to gather information about the anti-Semitic statements” which could constitute an offence relating to the exercise of fundamental rights and public freedoms, according to a statement received by AFP.    

“It is unacceptable that such serious anti-Semitic manifestations go unpunished,” said Isaac Benzaquen, head of the Spanish Federation of Jewish Communities, indicating that a complaint had been filed.

Israel's ambassador to Spain, Rodica Radian-Gordon, also tweeted her condemnation, saying the statements were “repugnant and have no place in a democratic society”.

And the American Jewish Committee (AJC) described the rally as “horrific”, calling on the Spanish government on Twitter “to censure these groups endangering democracy”.

At least 200,000 Spanish Jews were forced into exile by King Ferdinand and Queen Isabella in 1492. Known as Sephardim — the Hebrew term for Jews of Spanish origin — many fled to the Ottoman Empire or North Africa and later to Latin America.   

Today the Jewish community in Spain numbers around 40,000 people, community sources say.