Authorities on Wednesday called off the traditional New Year's Eve fireworks display in the capital, citing fears of a militant attack, Reuters reported.
Police carried out searches at six locations in the Belgian capital and one just outside the city, seizing computers, mobile phones and equipment for airsoft, a sport involving guns that shoot non-lethal plastic pellets.
Two Belgian nationals arrested earlier this week are being held on suspicion of planning a terrorist attack, prosecutors said. A court on Thursday extended their custody for a month.
Both are members of the Kamikaze Riders, a Brussels-based motor bike group whose members are mostly of North African origin and carry out bike stunts which can be seen in online videos.
Read alsoDW: EU plans tough new anti-terrorism lawsSome Belgian media say the group harbors Islamic State sympathizers and that the search for other group members had led Brussels to cancel Thursday night's planned firework display.
The presumed ringleader of the Paris attackers, Abdelhamid Abaaoud, was Belgian and grew up in the poor Brussels district of Molenbeek. Two further Paris attackers had been living in the Belgian capital.
Federal prosecutors said on Thursday that a 10th person had been charged with involvement in the attacks after 10 mobile phones were found during a search at a Molenbeek residence on Wednesday.
