The Wallonie-Bruxelles Enseignement administration body on Monday shut at least 27 schools in Brussels and the neighboring Brabant region after a bomb alert on Sunday evening.
Belgian media reported that the sender of the alert had demanded 10 million euros to reveal the location of five bombs.
"The arrested person, who is of Moroccan nationality, was questioned and admitted the deeds to the Moroccan authorities. The investigation's initial conclusions do not point to terrorist motives," the office said in an e-mailed statement.
The prosecutor's office in Brussels said it was continuing the investigation in cooperation with Moroccan authorities to find out the suspect's motives.
The schools reopened on Tuesday.