"The indications that led to the arrest of Faycal Cheffou were not substantiated by the ongoing inquiry. As a result, the subject has been released by the examining magistrate," the federal prosecutor's office said in a statement, without giving further details.
Belgian media had identified the man as Faycal Cheffou who claimed to be a freelance journalist.
Cheffou was charged on Saturday with "taking part in a terrorist group, terrorist murder and attempted terrorist murder".
Belgian police earlier today released some of the CCTV images in a bid to identify the suspect.
In the video, a man in a hat and white jacket is seen pushing a trolley with a large bag through the departure hall next to bombers Ibrahim El Bakraoui and Najim Laachraoui.