Police have uncovered a major cannabis-growing operation in a disused factory on a former airfield.
They found 2,000 cannabis plants, worth about £250,000, being cultivated at the site.
If the operation had gone undiscovered, the plants could have been harvested two or three times in a year and put a huge amount of cannabis on to the streets.
The find was made in an apparently disused factory on a former airfield in Dalby Road, outside Melton.
Police were called there in the early hours of Monday after reports of suspicious vehicle movements.
They believe the vehicle spotted there might have been part of an effort by other criminals to raid the cannabis farm.
When police arrived, they found cannabis leaves scattered near one of the factory units.
They followed the trail into a portable building attached to the building and found a hidden door which led into the main growing area.
When officers opened two 40ft containers they found more plants, this time recently planted seedlings, and cultivation equipment, including lighting rigs and ventilation pipes.
Sergeant Kev Pulley, of Melton police's safer neighbourhood team, said: "It was one of the most professional cannabis factories I have ever seen.
"This is serious organised crime. It's a massive result for the community of Melton and Rutland because it will inhibit the supply of the drug here and, perhaps, across the region."
Joe Orson, county councillor for the area said: "This is a significant find. It demonstrates the value of phone calls to the police about any form of suspicious activity."
Three men, who were detained away from the site later on Monday, have been questioned and released on police bail.
Police have urged people to call them if they believe a property is being used for cannabis cultivation. Officers said signs to look out for included:
Windows obscured at all times.
Heavy condensation on windows.
Lights being used at odd times.
Deliveries of large items late at night.
Information about drugs offences can be passed to police by calling 101. Alternatively, call Crimestoppers anonymously on 0800 555111.
