Hundreds of cannabis plants have been found at a property in Crawley.
Police said two men have been arrested after the cannabis growing site was discovered.
A spokesman added: “At 4.10pm on Sunday (February 2) police were called to a report of intruders at an address in Tennyson Close, Crawley.
“Two suspects were seen on a neighbour’s CCTV walking down the road, and a short time later were seen leaving the location with a number of bags.”
Officers found some 800 cannabis plants in various stages of cultivation at the address, he added.
The spokesman said: “Two men, aged 38 and 35, were arrested on suspicion of production of cannabis and after being interviewed were released under investigation.”
Detective Sergeant Ian Warncken added: “Our thanks go to vigilant neighbours who brought this matter to our attention.
“We would also like to hear from anyone else with information that may help the investigation. Please contact us in confidence online or by calling 101, quoting serial 986 of 02/02.”