The operation by East Sussex Fire and Rescue Service continues at Newhaven.
Fire crews were called at 9.32 on 8 August 2020 to reports of a fire at an industrial unit on Beach Road.
As of 11.30, 12 fire engines are being supported by water carriers and aerial appliances.
Crews are working hard to tackle the fire.
There are no reports of injuries and the building has been evacuated.
Members of the public are being asked to avoid the area and keep doors and windows closed due to the smoke.
It is too early to say what caused the fire.
Sussex Police are among the other agencies supporting at the scene and in the local area.