Over 350 cannabis plants were unearthed during a police raid in Todmorden.
Two men - a 31-year-old and a 53-year-old from the Oldham area - have been arrested on suspicion of producing cannabis following the raid which took place at a commercial unit at 3pm on Wednesday.
Both men were quizzed about the discovery on Wednesday night, but have since been released on bail pending further enquiries.
Acting Sergeant Ryan Stockton, of the Valley West Neighbourhood Policing Team, said the discovery was made following a tip-off.
“I’d encourage people to come forward if they do have any information about illegal activity taking place in their area,” he said.
“We do take people’s concerns seriously and we that is why we are so successful.”
Anyone with information can contact the police via 101 or Crimestoppers, in confidence, on 0800555111.”