On Sunday afternoon, up to 500 people, mostly French men, waited outside a venue in the Brussels suburb of Anderlecht, many holding pineapples.

They had come to attend a meeting that had been labelled by a local anti-hate group as the worst gathering of antisemitic propagandists in Belgium since the Second World War. Among those due to attend the meeting were antisemitic comedian Dieudonné M’bala M’bala and polemical author Alain Soral.

The demonstrators intended to used the pineapples as a prop while singing a song mocking the Holocaust. “Yes we brought pineapples,” said one. “It’s a reference to Dieudonné’s song ShoaNanas (a double-meaning referring to “Hot Pineapple” and also “Shoah Girls”).

“We think is disgusting that people want to make money out of the suffering.”

But Belgian authorities banned the so-called “First European Congress of Dissent” hours before it was due to start. Outside the building, the men, of whom many were of African and North African origin, rioted.

“Look around you, look at our faces. I see people from every community, every race and every religion. Where are the fascists? Fascism is based on a so-called superior race, but there’s no superior race here,” said one protester.

After a standoff lasting several hours, anti-riot police used water cannons to clear the demonstrators.

“The ban is unacceptable. The mayor thinks he’s Adolf Hitler,” said lawmaker Laurent Louis, who heads far-right movement ‘Get Up Belgians’ and had organised the event.

Knowing the meeting was in danger of being banned, Mr Louis kept it secret until the last minute. Authorities discovered the venue a day before it had been due to take place.

“Authorities acted quickly. This is Brussels, the heart of Europe, and such an antisemitic event would have been a terrible symbol,” said Maurice Sosnowski, head of Belgium’s main Jewish umbrella group. “This ban is a victory in the sense that Belgium has shown that people can’t just make any hate comment they want. It’s a strong signal.”

The mayor, Eric Tomas, issued an order prohibiting the meeting and counter protests on Sunday, saying they were a threat to public order.