MORE than 40 firefighters spent Sunday afternoon tackling a major warehouse blaze in the heart of a busy shopping area.

Thick black smoke billowed 150 feet up into the air from Portrack Workshops on North Tees Industrial Estate in Stockton and could be seen several miles away.

It is not yet known how the fire started and investigations into the cause and the extent of the damage continue today.

The area, which was busy with shoppers, was closed to the public while firefighters fought to keep the blaze under control.

At the height of the blaze, which started at about 2.45pm, there were seven fire engines, two hydraulic platforms, two emergency tenders and around ten police vehicles.

District manager at Stockton fire station, Phil Lancaster, said that an initial three fire crews arrived - but realising it was a massive blaze, called for back-up.

"There are a number of businesses inside the property so we are not sure what happened. I do think though there was some timber that went up and that didn't help us," he added.

"Fortunately there was no wind and that really helped us as the smoke just went straight up, otherwise we may have had to shut the A19 to as far back as the A174."

Eye-witnesses say they believe the area is used for illegal fly-tipping and this may have been partly to blame for the fire, a claim which was denied by Mr Lancaster.

He said: "I have not been made of any fly-tipping, and we are carrying out investigations to determine the cause of the blaze."

Malcolm Bendelow, who works at the nearby MSV, was one of those to first see the smoke.

He said: "I saw small wisps of smoke come from the building and from behind it, and then the next thing I knew there must have been a rush of oxygen and the smoke just went up like a rocket."