A cannabis factory worth £80,000 was discovered at a farmhouse in Oswaldtwistle yesterday.
Officers seized 200 plants in the upstairs bedrooms on Pot House Lane after a warrant was issued.
Lighting and cultivation equipment were also found and enquiries are ongoing to find out who was responsible.
PC Kat Stokes, from Oswaldtwistle neighbourhood policing team, said: "This was a very sophisticated set up which had clearly been going for some time. Clearly someone has been tending to the crop on a regular basis and we are carrying out forensic enquiries to find out who was responsible.
"Id like to thank members of the public for bringing this to our attention and I hope people are reassured that the police do listen to concerns and will take action."
Anyone with information or concerns about cannabis in their community can contact police on 101 or Crimestoppers anonymously on 0800 555 111.