Officers raided an end-of-the-block house on Liverpool Road, Blackpool, yesterday, seizing more than 500 plants.

With an estimated street value of £200 per plant, the haul could have taken more than £100,000 worth of drugs off the streets.

Four people, two men, aged 32 and 36, and two women, aged 22 and 27, were arrested.

They were today being questioned by detectives on suspicion of production of class B drugs.

Detectives today told The Gazette the factory appeared to be "a professional set up".

Det Sgt Sean Burrell, who is leading the investigation, said: "We have made a significant discovery of cannabis plants at a house on Liverpool Road.

"The property is a three- bedroom terraced house and every room in the upstairs of the building had been turned over to the production of cannabis.

"This was a significant discovery and hails another success in our efforts to reduce illegal drug activity in Blackpool.

"We always welcome information from the public in our efforts to tackle this type of crime and I urge residents to pass any suspicions about drugs on to the police."

The raid took place at around 4.30pm on Wednesday and the discovery is said to have been prompted by "community intelligence".

It follows on from a series of raids throughout the week. Operation Abacus saw £21,000 cash seized along with a plethora of potentially lethal drugs including cocaine, Ecstasy, LSD and temazepam.

An imitation firearm was also seized as specialist officers raided 17 addresses in Grange Park, Layton, Blackpool, Ansdell and St Annes.

Ten suspected dealers were arrested.