DRUGS gangsters tried to disguise a huge cannabis farm with a company sign.

An industrial unit in Salford had a board on the front purporting to be a piping firm.

But behind the steel shutters was a vast cannabis operation.

Police raided the premises, in Kansas Avenue, yesterday and seized hundreds of plants.

The unit was kitted out with lighting, ventilators, and irrigation channels for the production of huge amounts of the drug.

One eye-witness to the raid said: "The sign on the unit has only been up a short while. It was obviously meant to be a cover for what was really going on. There are legitimate businesses next to the unit."

The huge sign says MLS Plastic Piping.

Police said two men had been arrested on suspicion of cultivating cannabis and officers are trying to find out who owns the property.

The raid is the latest of hundreds across Greater Manchester in the last year as police attempt to smash widespread cannabis farms in disused factories and suburban homes.

One witness said: "It was clearly a well established operation, the police were bringing out loads of equipment and plants at various stages of growth."

In 2007, 351 cannabis farms were closed down in Greater Manchester.

Figures showed that 61 of the drugs factories were controlled by Chinese or Vietnamese criminals. In an operation codenamed Dragonfly, police targeted large-scale cannabis production.

This year police have continued the raids and one of the biggest discoveries was inside a disused pub. More than 900 plants were removed from the Haxby Hotel, in Haxby Road, Gorton.

This week two Birmingham men were each given 21-month jail sentences for producing cannabis after £70,000 worth of the drug was found in the Lion Works building in Old Market Street, Blackley.