Avon and Somerset Police have seized cannabis plants worth more than £100,000 from a property in Clifton, Bristol.
Acting on information provided, the officers entered the property on Whiteladies Road on June 28 at about 10.20pm.
More than 300 cannabis plants were seized which have a street value of more than £100,000.
One man has been arrested on suspicion of production of a controlled drug.
Officers have continued to search the building today.
Police enquiries are continuing.