More than £1 million worth of cannabis plants have been seized after the police received a tip off from a member of the public.
Avon and Somerset Police discovered around 1,000 plants at an industrial unit in Kingswood, South Gloucestershire.
Electricity had been diverted from a nearby substation to power the equipment used to help grow the plants.
A spokesperson for the force has described those behind the operation as 'organised criminals' who were 'exploiting vulnerable people'.
Officers are now urging people to keep coming forward with information after their successful raid, which was a result of a public tip-off.
They are reassuring people that information can be disclosed anonymously.