Three people have been detained in a series of anti-terror raids in the Brussels suburb of Molenbeek, where some of the Paris and Brussels attackers lived or transited.
Spokeswoman for the Brussels prosecutor's office Ine Van Wymersch said on Saturday that four searches were conducted.
Ms Van Wymersch said "the action has ended. Nothing was found, no weapons, no explosives".
She declined to provide more details but said that the three would be questioned on Sunday to establish whether they should be charged or released.
Belgian authorities have been on high alert since suicide bombers attacked the Brussels airport and subway system on March 22, killing 32 people.