A 30-year-old man from Abertillery has been arrested on suspicion of arson after a blaze at a Crumlin crisp factory.
Workers at the Real Crisp factory on the Pen y Fan Industrial Estate in Crumlin had to be evacuated in the early hours of Thursday morning.
South Wales Fire and Rescue Service said it received a call at 3.18am to Sirhowy Valley Foods.
Sixty-five firefighters from 20 stations were sent to the incident. South Wales Fire and Rescue Service said that on arrival at 3.30am, three-quarters of the building was ablaze.