A spokesman for West Sussex Fire & Rescue Service said crews are on the scene of the incident at an industrial unit off Grevatt’s Lane in Climping.
He added: “Joint Fire Control received the 999 call at 1.11pm this afternoon and mobilised fire engines from Arundel, Bognor Regis, Chichester, Littlehampton and Worthing to the scene along with the Incident Command Unit from Haywards Heath and the Water Carrier from Burgess Hill.
“Crews have been making steady progress, making use of three jets to bring the fire under control.
“The incident has been scaled back, and we now just have two appliances in attendance from Selsey and Worthing.
“We would urge residents living nearby to continue to keep their doors and windows closed while this fire is brought under control.”