The Brussels police chief was knocked unconscious on Tuesday during clashes at the end of a major anti-austerity demonstration attended by around 50,000 people in the center of the Belgian capital.
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Police chief Pierre Vandersmissen was treated for a head injury after he was hit with a stone in the back by a red-clad man and fell to the ground during rock throwing by a few dozen protesters after most of the marchers had already disbanded.
With a pepper spray canister, Vandersmissen had been chasing people who had attacked police even though he was not wearing extensive protective gear.
He was taken to hospital and is expected to be released on Wednesday.
The demonstration was called to protest the center-right government’s social and economic policies, which trade unions say cut deep into the foundations of Belgium’s welfare state.