ARSONISTS are being hunted after a blaze ripped through a paper factory in Darwen last night.

About 70 firefighters from across Lancashire battled through the night to bring the fire at Stamford Converters, also known as Stamford Packaging, a paper and packaging plant in Exchange Street, under control.

As the factory was engulfed by fire, the explosion of a propane gas canister sent flames shooting 70ft into the air.

Police are treating the blaze as suspected arson and early today three pumps were still at the scene damping down, while a fire investigation team worked to determine the cause of the fire.

Det Sgt Ian Critchley of Darwen CID said: "In view of the time the fire started and the value of the property involved we are treating this fire as suspected arson."

Eight appliances attended the scene and two aerial ladder platforms poured water onto the factory from above while crews battled against the flames from the ground.

The major incident support unit, the environmental protection unit and the incident support unit were also at the scene at 9.40pm.

Sub Officer, Steve Ryan, said: "On arrival there was a lot of smoke in the street making approaching the building very difficult. The premises were secured and we had to break down a door and force our way through the roller shutters. There was obviously a very severe fire developing so we called for assistance. "We heard an explosion so our crew moved to the back of the yard and portable monitors were put in place along with the aerial ladder platforms at the front and back of the building." Firefighter Andy Steel was treated by paramedics after getting burning debris in his eye, but did not require hospital treatment.

Assistant chief fire officer John Williams, who headed a mobile control unit on the scene, worked with a team of officers and information from workers at the factory to locate nine remaining propane gas cylinders inside the building.

Iain Cardoo, 23, who has worked at Stamford Convertors for seven years and lives on Dove Lan, Darwen said: "I was watching the football when I heard the fire engines going past. I went out the front to have a look and saw all the smoke coming out.

"I went over to the crews because I knew where the gas bottles were and I was coming back when I heard the bang and thought one of them must have gone off." Mother-of-four Isabell Bramham, 28, from Olive Lane said: "I just heard a great big bang and I could see it was a blaze from my house. I ran round to have a look and saw smoke coming out of the roof."

By 11.30pm a large section of the building was on fire and the roof of the building had been burnt through.

Passing motorist Bob Waters, who contacted the fire brigade said: "You could see the flames in the distance from the M65."

Several streets surrounding the factory were closed to traffic and onlookers were told to keep behind a safe distance away.

Anyone with information should contact Darwen CID on 01245 353841.

Factory owner John Sutcliffe was unavailable for comment today.

Picture: Fire crews tackle the huge blaze (right) and the aftermath of the blaze.