A conservative conference in Brussels that was shut down by police for creating a “public disturbance” is taking emergency legal action.

The National Conservatism Conference, known as “NatCon,” had scheduled a variety of speakers, including Hungary’s prime minister, Viktor Orbán, the Brexit leader, Nigel Farage, and the former U.K. home secretary, Suella Braverman, per Politico, but shortly after the event started police arrived to shut it down. 

“We are legally challenging the order to shut down #NatConBrussels2 at the new, third venue,” the organizers wrote on X. “There is no public disturbance and no grounds to shut down a gathering of politicians, intellectuals, journalists, students, civic leaders, and concerned citizens. “

The order shutting down the event from the mayor of the Saint-Josse-ten-Noode district in Brussels, Emir Kir, reportedly cited NatCon’s “ethically conservative” views, and said that the event must be shut down “to avoid foreseeable attacks on public order and peace.” 

After seeing the proceedings and the press corps, NatCon organizers said, the police withdrew and began blocking access to the event from the outside.

“They only sent three police officers and so when the police walked in and all the cameras turned on them they got scared and they went back outside,” an Israeli-American philosopher and event organizer, Yoram Hazony, told the audience. 

Organizers warned attendees that if they left the venue, police would not let them re-enter.

“The police are not letting anyone in,” organizers wrote on X. “People can leave, but they cannot return. Delegates have limited access to food and water, which are being prevented from delivery.” 

In the days leading up to the conference, there had been several attempts to shut it down under pressure from left-wing politician, Politico notes, as well as threats of protest from left-wing activists.

A memo issued Tuesday from Alliance Defending Freedom International expressed support for the conference as it files an emergency legal challenge, noting that the mayor’s order shutting down the event violates freedom of speech and assembly.

“Open dialogue is supposed to be at the core of European politics; yet here in the capital of the EU, a thoughtful exchange on policy has been shut down by unilateral decree. This is a watershed moment where the true censorship crisis in Europe is on full public display,” ADF International’s executive director, Paul Coleman, said in a statement. “The crushing of political opinions opposed by those in power is something that should be relegated to the darker chapters of European history.”

Event attendees and speakers reacted to the police action with dismay at the state of European politics. “I’m here with like-minded democrats, democratically elected politicians, leaders and experts in their fields and we are here talking about the issues that matter to the British people,” Ms. Braverman told Sky News. “It’s a real shame that the thought police instructed by the mayor of Brussels has saw fit to try and undermine and denigrate what is free speech and free debate.”