Protests against the corona restrictions in Brussels with around 50,000 participants from home and abroad turned violent on Sunday.
Some participants threw stones and firecrackers, the police used tear gas and water cannons.
About 70 demonstrators were arrested.
According to the police, three emergency services and twelve demonstrators were hospitalized with injuries.
EU foreign policy chief Josep Borrell condemned the violence.
The clashes between protesters and police broke out in the EU quarter of the Belgian capital.
As some demonstrators threw cobblestones and firecrackers at police, officers used water cannon and tear gas to push back the crowd.
In the meantime, the emergency services were forced to seek shelter in a subway station.
Police said none of the three officers and 12 demonstrators who were taken to hospital with injuries were life-threatening.
During the riots, the glass front door to the headquarters of the EU foreign policy representative was smashed.
Borrell condemned the "destruction and senseless violence".
The movements World Wide Demonstration for Freedom and Europeans United for Freedom called for the demonstration.
They also expressly invited people from other EU countries to join the protest.
Participants waved Polish, Dutch and Romanian flags, among others.
The demonstrator Adolfo Barbosa, who had traveled from Portugal, spoke of a “health dictatorship”.
About 50,000 people gathered, according to the police.
It was the largest demonstration against the corona measures in Belgium in months.
The demonstrators carried banners with slogans against Belgian Prime Minister Alexander De Croo.
They also criticized the Corona passport, with which a corona vaccination or a negative test must be proven in numerous public institutions in Belgium.
"Freedom of expression is one of the foundations of our society" and everyone is free to express their opinion, explained De Croo.
"But our society will never accept blind violence and certainly not against our police forces." The demonstrators involved in the riots would be prosecuted, emphasized the head of government.
Brussels Mayor Philippe Close spoke of a "difficult day" in view of the violence.
In Belgium, the number of new infections every day had risen to more than 60,000 in the past week.
The authorities therefore spoke of a corona "tsunami".
However, because of the usually milder course of infection with the dominant omicron variant and the high vaccination rate, the Belgian health system is not as heavily burdened as during previous corona waves.
Prime Minister De Croo therefore announced on Friday that restaurants and bars would be allowed to extend their opening hours again.
However, discotheques would have to remain closed.