A police spokesperson says despite the suspect's young age, the court decided there was good reason to think he would interfere with the investigation. And they do not think he acted alone.
"If you're 15 years old then you don't have the knowhow to make explosives. So we assume he wasn't alone," says police spokesperson Ewa-Gun Westford to news agency TT.
Although there have been several suspicious explosions in Malmö recently, the 15-year-old is only suspected of one.
He has been arrested for destruction that endangers the public and is also suspected on likely cause for causing the Christmas Eve bombing alone or with help. This is the lower of the two degrees of suspicion.