The international airport in Brussels is due to partially reopen on Sunday following suicide bombing attacks that killed more than 30 people in the Belgian capital last month, its operator said.
On March 22, two men blew themselves up in the departure hall of the Brussels Zaventem airport, while a third set off an explosion at a metro station near the city's European Union headquarters.
The resumption of air traffic will start with three "symbolic" passenger flights to Faro, Turin and Athens, the company said.
Rioting took place Saturday night in the Brussels district of Molenbeek, home to the organizers of the attacks in the Belgian capital and in Paris in November, Belgian media reported.
Some 400 people gathered near the district's administrative building, media reports said. When 100 people tried to march into the city centre, they were pushed back by police.
Stones and waste containers were then thrown at the security forces, RTBF radio reported.
Together in Molenbeek and on the central square in front of the Brussels Stock Exchange, where unsanctioned demonstrations took place, some 100 people were arrested, Belgian media reported.
The terrorist attacks on Brussels on March 22 in which 32 people died have increased tensions in the Belgian capital.
Right-wing extremists called for a demonstration in the district of Molenbeek, which is home to many mostly Muslim immigrants as well as the Paris and Brussels attackers. The city authorities had banned the demonstration.
Left-wing activists had gathered in front of the stock exchange.