Police are treating as suspicious a fierce blaze which wrecked a disused caravan factory.

Fire broke out in the late afternoon on Tuesday in the former Elddis works in Delves Lane, on the outskirts of Consett, and took hold throughout the 150sq m building.

At its height, flames leapt 30ft into the sky and a plume of thick black smoke could be seen from several miles away.

Fourteen pumping appliances and 90 firefighters were sent to the scene from nine fire stations across County Durham.

Back-up was provided in the rest of County Durham and Darlington by neighbouring Tyne and Wear and Cleveland brigades.

Police closed off a quarter mile stretch of Delves Lane and urged people to close windows to prevent smoke seeping into their homes.

Assistant Divisional Officer Andy Mackay, of Durham and Darlington Fire and Rescue Brigade, said crews were on scene through the night to damp down at the gutted premises.

"We knew there was no one in there from the start, so it became a fire containment exercise," he said.

"There were no chemicals involved. But, because of the products of combustion, police were asking people in the vicinity to keep their windows shut."

Margaret Stemp, landlady of the nearby Black Diamond pub, said: "I was coming in from Castleside area when I saw it and I thought: 'Oh, my God.'

"I thought it was my place at first but then I realised it was the old Elddis factory."

Elddis, part of the Explorer group, has transferred caravan production from the site to the former Amoco Fabrics plant, further along Delves Lane, in recent years.