A 38-year-old Belper man has been arrested in connection with a suspected arson attack at a factory in the town.
The man was later released on police bail without charge following the blaze at Coutaulds, Bridge Foot on Tuesday, August 27.
A spokesman for Derbyshire Police said the incident is being treated as arson and appealed for people to come forward with any information.
Fire crews were called to the factory at 10.55pm and found cardboard and debris had been set alight. They took about an hour to put out the fire.
A spokesman for Derbyshire Fire & Rescue Service said: “Firefighters from Belper and Duffield attended a report of a building fire at West Mill, Belper.
“The incident involved a factory fire, small fire in a warehouse and a single storey 80 metres by 80 metres building.”
Firefighters used breathing equipment and also a thermal imaging camera to check the rest of the building once the main fire had been put out. They also ventilated the affected building.
In May a fire destroyed a disused warehouse at the former site of chocolate company Thorntons in Belper after a suspected arson attack.