Riot police in Brussels Sunday used water cannon to disperse a crowd defying a ban on a gathering of controversial far-right figures including French comic Dieudonne, which critics called an "anti-Semitic hatefest".

Citing a threat to public order, the mayor of the Brussels district of Anderlecht banned both the meeting and any protests connected to it.

But organizers of the so-called "European Dissidents' Congress" - a Brussels bookshop and a group called "Debout les Belges!" (Belgians, Rise up!) - urged supporters to head to the venue for "a surprise", sparking the standoff with riot police.

"It's over. Everyone should disperse calmly," said Laurent Louis, the 34-year-old far-right lawmaker and founder of "Debout les Belges", after police forcefully broke up the crowd of about 500 protesters without making arrests.

"They're coming down on us, I don't want any injured," Louis told the crowd, though about 40 supporters remained outside the venue later.

The event was to bring together a string of far-right figures, including the comedian Dieudonne M'bala M'bala, who has faced repeated accusations of anti-Semitism, Holocaust denial and incitement to racial hatred.

Dieudonne, a longtime cult figure in France, shot to a wider notoriety when footballer Nicolas Anelka performed the comic's signature quennelle gesture during a match in Britain.

The quenelle, a stiff armed pose, is defended by its users, including event organizer Louis, as an "anti-establishment" gesture but critics see it as a disguised Nazi salute. It is regularly used by a wide range of anti-Semitic groups, including neo-Nazis and Islamists, who often post pictures online of themselves performing the gesture outside Jewish venues or at holocaust memorials.

Louis had kept the venue a secret until the last moment to prevent it from being closed down.

The organizers immediately challenged the ban before Belgium's state council, which was to issue a fast-track ruling, and around 200 supporters and critics of the event had rallied in Anderlecht early Sunday afternoon, many performing the quenelle.

The Belgian League against anti-Semitism, LBCA, Friday filed a complaint before the Brussels prosecutor against what it called "a day of hate, that would serve as a platform for the worst gathering of anti-Semite authors, theorists and propagandists that our country has seen since the end of World War II."

The Nazi-hunting Simon Wiesenthal Centre rallied behind the calls for a ban, dubbing the event an "anti-Semitic hatefest".

"The fact that this hatefest is to be held in Brussels, the capital of Europe, the seat of its Parliament... is a threat to democracy reminiscent of the 1920s Weimar Republic, which brought Europe to the Nazi abyss," the centre's director for international relations Shimon Samuels warned in a statement. Louis had remained defiant despite the ban.

"There are people coming from Switzerland, France, Strasbourg, from all over," he told Belgian television early on Sunday. "I will be there to welcome them and if they want to arrest us, then arrest us."

"Our guests have confirmed they will be coming, and in any event - ban or no ban - you can meet them and spend an unforgettable day," Louis had written on his Facebook page.