A DETACHED house containing a £300,000 cannabis factory may have been purpose-built to produce drugs, according to police.

Around 600 plants were found yesterday in the Blackburn property set back off the main road behind seven-foot concrete walls.

But behind the roller shutters of two ‘garages’ was a plasterboard wall and officers could hear the whirring of fans from inside.

When they raided the property at 9am, they found a sophisticated hydroponic system over two floors and the attic.

Police said there were no rooms in the house, just open floors filled with the drugs set-up.

Just short of £20,000 worth of electricity had been bypassed in six months to supply constant heat, light, water and air filtration, police said.

Shaun Cooney, 41, was arrested on suspicion of cannabis cultivation.

Mr Cooney is believed to own a terraced house in Bolton Road and the unoccupied detached property on land behind it.

Blackburn South West neighbourhood Sergeant Paul Schofield said: “One of lines of inquiry we are looking into is whether it was built solely for the purpose of a drugs factory.

“It looks as if that’s the case: the facade of a house being used as a drugs den.

“What we’ve discovered is one of the biggest cannabis factories we’ve ever had and it’s now off the streets.

“There must have been many, many thousands of pounds spent on the set up inside. It was highly sophisticated.

“We’re looking into how long it has been used as a factory. It could be 12-18 months, but we may never know.”

Police received anonymous information via Crimestoppers and sent up a police helicopter to pinpoint the heat source.

Two dogs – a Lurcher and a Staffordshire bull terrier – were being kept in a shed next to the house, police said.

The building has been the subject of a planning wrangle.

According to Blackburn with Darwen Council’s website, in October 2008, Mr Cooney resubmitted an application to Blackburn with Darwen Council’s planning department for a ‘replacement garage with first floor games room and study’.

A decision to refuse the application was appealed by Millbrooke Construction Ltd.

That appeal was upheld by Inspector David Pinner from the Bristol-based Planning Inspectorate in January 2009 with conditions preventing the ‘garage’ being used for residential purposes.

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