Fifteen fire crews tackled a blaze at a processing plant for British Sugar.
Suffolk Fire and Rescue Service were called to the fire, which involved conveyor belt systems, at the factory in Bury St Edmunds, Suffolk, at 15:50 GMT.
The service said the blaze covered an area of approximately 30m (100ft) square over several floors.
"There are no casualties at this incident and crews will remain on scene for some time," a spokesperson said.
The fire service worked with British Sugar firefighters to extinguish the blaze.
In a tweet, the service said "swift intervention" by both teams meant "the incident was dealt with quickly".