Following the Red Devils’ 2-0 defeat in Qatar police were forced to seal off parts of the nation’s capital as they tried to disperse crowds.
Sky reports that officers deployed water cannons and fired tear gas to halt the rioters.
The report adds bricks were thrown at cars and steps were set on fire. One person suffered facial injuries, according to Brussels Police spokeswoman Ilse Van de Keere.
It’s not clear what sparked the riots or how many people have been detained.
The mayor of the city, Philippe Close, urged football fans to stay away from the city centre, adding that authorities were doing their utmost to keep order in the streets.
“I strongly condemn the incidents that occurred this afternoon,” Close said.
“The police have already acted harshly. So I advise supporters not to come to the centre. The police are doing everything they can to maintain public order.”
The win for Morocco was one of the biggest upsets at this World Cup and was celebrated by fans with roots from the country.
Romain Saiss put them ahead on 73 minutes before Zakaria Aboukhlal sealed the famous victory in stoppage time.
The result, plus Croatia’s 4-1 victory over Canada means Morocco will are due to join Croatia in the last 16.
However, Belgium will seal their place in the last-16 if they beat Croatia on Thursday, kick-off 3pm.