A 22-year-old man from Marsa was arrested after a drug find late on Monday afternoon.
The police found heroin, cocaine and cannabis in his possession, as well as cigarettes whose excise duty had not been paid.
The police said some of the drugs were packed and ready for trafficking.
In connection with the investigations, the police also arrested a 27-year-old man from Marsa and a 24-year-old woman from Ħamrun, who were caught with cannabis in their car.