A French police source said the raids in the Brussels suburb of Schaerbeek were related to the arrest of 34-year-old Reda Kriket in Paris yesterday, who was found with heavy weapons and explosives in his apartment.
Police had completely sealed off the area in the Schaerbeek district, an AFP reporter at the scene said.
Schaerbeek is where police found a bomb factory after the Brussels airport and metro suicide attacks on Tuesday and from where the three airport attackers set off that morning.
Two explosions were heard during the operation and bomb disposal experts were on site, reports said.
The latest raid forced Belgian Prime Minister Charles Michel and Foreign Minister Didier Reynders to cancel a wreath-laying ceremony with visiting US Secretary of State John Kerry at the airport, an AFP reporter travelling with Kerry said.
During a series of raids in Schaerbeek on Tuesday night police found 15 kilos of high explosive, bomb-making chemicals and an Islamic State group flag.
