Dozens of cannabis plants have been seized by police in two separate raids on properties in Doncaster.
Houses in Mexborough and Hexthorpe were at the centre of the action, when police used warrants to get into the properties.
But police chiefs are still looking to find who the people were behind the cannabis factories and they are appealing for information from the public.
Officers found 19 cannabis plants at a house on Laburnum Road, in Mexborough.
They were called to the address after it was broken into.
They arrested and charged three men with breaking into the property but are still investigating where the plants came from.
In a separate incident, officers raided a house on Abbott Street, Hexthorpe, because of concerns over the activities which were going on there.
Again, 19 cannabis plants were seized by officers after they had searched the property.
It is unclear at present who owned the plants, and no arrests have yet been made.
Police estimate the value of the plants in each of the raids was in the region of £19,000.
South Yorkshire Police Supt Eddie Murphy said: “Enquiries into the incidents are ongoing.
“We would like to hear from any witnesses who may have seen who has been coming and going from those two addresses.”
All of the plants which were discovered in the raids have been seized and destroyed by officers.
Cannabis is classified as a class B drug, and is in the same legal category as drugs such as amphetamines, barbiturates, ccodeine and mephedrone.
The Government says, under the law, those involved in the supply or production of the drug could face up to 14 years in prison, an unlimited fine or both.
Those in possession of class B drugs could face up to five years in prison, an unlimited fine or both.
Call police on 101.