Belgium police launched a manhunt for a suspect they believe made the suicide vests.
The man, named by Belgian media as Mohamed K, is wanted “even more than Salah Abdeslam” – who is currently being hunted down by French authorities.
Mohamed K is originally from the Caribbean but had been living in the northern French town of Roubaix.
Reports suggest French police warned authorities in Belgium about the alleged bomb maker.
Authorities believe the alleged bombmaker may have fled France and is currently hiding out in Belgium.
A former French intelligence official said: “A munitions specialist is someone who is used to handling explosives, who knows how to make them, to arrange them in a way that the belt or vest is not so unwieldy that the person can’t move.
“And it must also not blow up by accident.”
A Belgian security agency said: “Even more than Salah Abdeslam, he is the man we need to find as quickly as possible”.