One counter-protestor was injured at the demonstration, for which police permission had not been given, reports TT.
“We have taken the arrested individuals to the police station,” police spokesperson Hans Lippens said.
The spokesperson confirmed that 15 individuals were detained, of which one was arrested for violent behaviour towards police.
In the early hours of Saturday, police stopped a car after its passengers had hung a banner with a right-wing extremist message over the E20 motorway, TT reports.
A number of flares and fireworks were confiscated from the car, Lippens confirmed.