The likes of Hungarian Prime Minister Viktor Orbán, French far-right candidate Eric Zemmour and the UK's former Home Secretary Suella Braverman were all due to speak at the two-day National Conservatism (NatCon) Conference.
Brexit Party founder Nigel Farage was addressing the crowds at the Claridge venue in the Belgian capital when Brussels police moved in with an order to close down the event around 12.30 CET on Tuesday.
A Euronews reporter was on the ground as a police officer told the event organisers that "the authorities have decided to shut down the event," and that he was present on-site to enforce that decision.
The officer added that he had a three-page document outlining the authorities' decision to order the shut-down, following a request from the local mayor
Emir Kir, the mayor of the Saint-Josse Ten Noode neighbourhood of Brussels, confirmed on social media platform X that he had issued the order to "guarantee public safety."
"The far right is not welcome," Kir said.
Two other Brussels venues, including the famous Sofitel Hotel near the EU institutions, had in recent days refused to host the NatCon conference.
Hours before the conference was due to be held at the Sofitel hotel in the Etterbeek neighbourhood, its mayor Vincent de Wolf had notified the venue about the speakers and nature of the gathering, sparking a last-minute decision to break the contract.
Farage told the crowds that the venues' decisions to cancel were "absolutely outrageous."
According to the organisers, some 600 attendees were expected at the venue on Tuesday.
