The police are holding a 34-year-old man from Mosta after he was allegedly caught cultivating cannabis plants in a field at Ta' Qali.
The discovery of the plants in a well-hidden pit and cannabis resin in a room nearby was made after the police had been trailing the suspect for some time.
While police officers were monitoring the suspect's movements on Tuesday evening, the latter was noted driving his car in fields near Ta' Qali.
The car was searched by the police who found a number of fresh cannabis leaves in a bucket and some empty jerry cans. A subsequent search in a number of fields led the police to a pit where the plants were found.
The police also came upon about 220 grammes of cannabis resin in a room nearby which is used by the suspect. The resin was ready to be trafficked, the police said.
Magistrate Doreen Clarke has opened an inquiry.