Keynote speakers at the 'national conservatism' conference include the eurosceptic populist Nigel Farage
Keynote speakers at the 'national conservatism' conference include the eurosceptic populist Nigel Farage AFP

A Brussels gathering of hard-right European politicians resumed Wednesday for a second day headlined by Hungarian leader Viktor Orban, after a top court scrapped a local ban widely denounced as an assault on free speech.

The local mayor in the Brussels district hosting the "national conservatism" conference tried to shut it down Tuesday citing a threat to "public security", with anti-fascist protesters vowing to target the event.

But Belgium's top administrative court sided with organisers overnight and overturned the ban, saying it violated the country's constitutional right to peaceful assembly.

Despite the shutdown order, the conference -- whose attendees include far-right figures and elected officials from across Europe -- had limped on through Tuesday with police blocking new attendees from entering.

France's firebrand former presidential candidate Eric Zemmour -- who was among those barred from entering -- was back on day two, and preparing to take the stage.

"Thanks to God, thanks to the pressure we exerted, thanks to the scandal in all of Europe, Europe has shown that it was still the continent of liberal democracy, and of the rule of law," Zemmour told reporters on site.

Hungary's Prime Minister Orban was to deliver the keynote address on Wednesday before attending a summit of EU leaders, having vowed "we will not give up".

Emir Kir, the mayor of Brussels' Saint-Josse district, had invoked safety issues for the ban, but he also wrote that the far right -- which is predicted to surge in EU-wide elections taking place in June -- was "not welcome".

His order drew broad condemnation, with Belgium's Prime Minister Alexander De Croo slamming it as "unacceptable", and British counterpart Rishi Sunak calling it "extremely disturbing".

Brexiteer Nigel Farage, who delivered a headline address on day one, had denounced it as "monstrous".

The "NatCon" organisers had been scrambling for a place to host their event since Friday evening, after its first two choices of venue abruptly pulled the plug, fearing disruption.

The Saint-Josse mayor said he took note of the court ruling, while defending his initial decision and vowing to remain "vigilant" with regard to any threat to public safety.

Although a risk assessment body had advised him of a "medium-level" threat to the event, the court said the mayor should have responded by reinforcing public security -- not by cancelling a private event.

"The authorities should at least have tried to protect the people exercising their constitutional right to assembly," said the court.