Police have swooped on three large-scale cannabis factories in Bradford in just two days, seizing plants with an estimated street value of £250,000.

The latest raid was on a property in Lower Grange yesterday just before 8am when officers from Bradford Drugs Team arrested and charged two men, a 19-year-old and 22-year-old, with production of cannabis.

They are due before Bradford magistrates today.

Detective Inspector Neil Benstead, from the District Drugs Team, said cannabis factories were elaborate operations and could not be run in residential streets without being noticed.

He said: "There are many ways to spot a potential cannabis factory and we want people to familiarise themselves with these warning signs so they can be our eyes, ears and noses on the ground.

"Most cannabis factories will emit a strong and unusual smell. Neighbours may hear a lot of banging noises as the factory is set up and see people coming and going with bags of fertiliser and compost and other equipment such as powerful lights.

"It is likely the curtains will be kept closed at all times but bright lights may appear to be left on around the clock. Residents living in the street are again likely to see various comings and goings when the crop is harvested, such as bags being loaded into a vehicle."

He also appealed to landlords to be on their guard: "If the tenant always pays in cash and does not allow you access to the property then let us check it out."

Anyone with information should dial Dob in a Dealer on 0800 555 111.