In an operation led by Lancashire Police's serious and organised crime unit, officers targeted seven retailers across Lancashire.

They included two in Blackpool - Grow Republic on Church Street and Little Amsterdam on Springfield Road.

All premises visited were suspected of selling equipment used for growing cannabis, such as seeds and books on how to cultivate the drug.

Twelve people were arrested on suspicion of incitement to produce cannabis and other related offence and were being questioned by police yesterday.

Det Chief Insp Steve Mounsey, from the Serious and Organised Crime Unit, said: "During 2007 an emerging picture developed of a number of retail premises within Lancashire which were knowingly selling equipment for use in the unlawful production of cannabis.

"The production of cannabis is unlawful and Lancashire Police is committed to disrupting this type of criminal activity within its communities.

"The premises targeted today have been selected as they are locations where it is suspected hydroponics equipment has been knowingly sold or offered for sale for the sole purpose of producing cannabis.

"The fact these premises exist in five towns within Lancashire and provide everything necessary, including cannabis seeds, carbon filters for the purpose of disguising smell and books on cannabis production, illustrates the scale of the problem."

One neighbour, who did not wish to be named, saw Grow Republic being raided.

She said: "There were two big blue wagons and then more came down. The police really seemed to be tearing the place apart.

"It was very exciting, it was like something off CSI. We saw two men taken away by police."

As well as Blackpool, raids were carried out in Preston, Darwen, Burnley and Walton-le-Dale.

In the past two years police have raided a number of domestic properties across the Fylde coast after they were transformed into cannabis factories by far eastern crime gangs.

From January 2009, cannabis is to be reclassified as a Class 'B' controlled drug.