Brussels police today said that they will carry out the directive to shut down the National Conservatism Conference.
The event in the Belgian capital is still going on, according to the organizers, although admission is no longer permitted.
Local officials declared that the conference should not take place due to worries about public safety.
Right-wing politicians from over Europe are expected to attend the summit, including Nigel Farage and Prime Minister Viktor Orban of Hungary.
The main speakers included far-right French politician Eric Zemmour and former UK
The National Conservatism Conference is a global movement that supports conservative values that it argues are being "undermined and overthrown." It is organized by the Edmund Burke Foundation, a think tank. It is also against more integration inside Europe.
The conference's stated goal was to unite "public figures, journalists, scholars, and students" who comprehended the relationship between nationalism and conservatism, as well as national customs.
However, the local mayor of the area, Emir Kir, said in a message to the organizers that some of the conference attendees on Tuesday have anti-gay and anti-abortion beliefs.
Mr Kir wrote on X: "The far right is not welcome."
"Bearing in mind the aim of this event is to bring together personalities from the media, academic and cultural world, as much as political figures who share a so-called 'national conservative' vision towards society; that among these personalities there are several particularly from the right-conservative, religious right and European extreme right," his statement said.