Police fired water cannons and tear gas into the protestors, who were fighting against enforced Covid booster shots by hurling firecrackers and paving stones. They said more than 60 people have been arrested, while three officers and 12 demonstrators were taken to hospital.
Protestors were seen assaulting the European External Action Service’s (EEAS) office, launching stones and metal poles at the glass windows and doors.
The EEAS tweeted: “The violence witnessed today in Brussels and the attack to our premises is a shameful violation of everything we stand for as EEAS and EU.
“We are grateful for the tireless work of @federalepolitie @policefederale and we will keep defending peaceful paths of freedom of expression.”
The service’s Secretary-General Stefano Sannino added that the protest was “despicable.”
Despite a record number of infections, Belgium had announced a slight easing of Covid restrictions on Friday.
However, they also said people must have booster shots five months after their vaccinations to keep passes for bars, cinemas and many other public spaces.
One of the protesters’ placards read: “I’m not an anti-vaxxer, I’m an anti-dictator.”
Reuters reported that protestor Caroline van Landuyt, who had been vaccinated, said: “I’m angry about the blackmail that the government is doing, mostly for the young people but for everybody, but mostly for the young people, they are really blackmailing that everybody has to go for the vaccine.”
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Josep Borrell Fontelles, who has been leading the EU’s Brexit negotiations with UK Foreign Secretary Liz Truss, tweeted: “Strongly condemn the senseless destruction and violence at the manifestation in Brussels today.”
The violent scenes were similar to clashes seen last November, in which roughly 35,000 protestors descended on Brussels’ streets against Covid restrictions.
Belgium is facing a fifth wave of COVID-19 infections, with the peak not expected for at least a couple of weeks.
The EU’s health agency said on Friday that Omicron had now become the dominant variant circulating in the bloc and some neighbouring countries.
89 percent of Belgian adults are fully vaccinated and 67 percent have also received a booster shot.