Additional Chief Judicial Magistrate Md Mostafizur Rahman gave the order on Tuesday after rejecting Nazmul's bail petition.
The case's investigation officer Abdul Awal had sought seven days to question the accused.
Police arrested Nazmul on Friday night from Savar for allegedly inciting workers and helping create unrest in the garments industry in Ashulia.
Nazmul is the Savar correspondent of News 24, Ekushey TV and Daily Bangladesh.
Also read- Police arrest ETV journalist over Ashulia unrest