Three people have been arrested in South Auckland in a police operation targeting the Tribesmen gang.

Police searched four properties in Flatbush, Otara and Manurewa, finding cannabis and ephedrine - which is used in the production of methamphetamine.

The confiscated cannabis holds a street value of almost $20,000, and the ephedrine, when used to make P, could potentially have fetched $375,000.

A 21-year-old patched Tribesmen and two 29-year-olds now face charges of possession and supply of illegal substances.

Detective Senior Sergeant Albie Alexander said drugs are one of the major factors in organised crime, and a major focus for his team.

"Getting this off the streets certainly goes some way to helping us fighting that battle."