West Coast Police have arrested three people in relation to Operation Joaquin, an investigation targeting the sale and supply of methamphetamine in the region.
Acting Detective Senior Sergeant Lex Bruning said four search warrants were executed on Wednesday in relation to the operation with the assistance of the Armed Offenders Squad.
Three of the addresses were in Greymouth and one was in Christchurch.
Methamphetamine, cannabis, cash and a loaded sawn-off firearm were seized.
A 32-year-old male and his 34-year-old female partner from Runanga have been jointly charged with conspiring to supply methamphetamine, possession of methamphetamine for supply and unlawful possession of a firearm.
They have also been individually charged with multiple offering to supply methamphetamine and were due to appear in the Greymouth District Court on Wednesday afternoon.
Bruning said bail would be opposed.
A 53-year-old male, also from Runanga, has been charged with conspiracy to supply methamphetamine, eight counts of offering to supply methamphetamine, cultivating cannabis, and offering to sell cannabis.
He is set to appear in Court on Thursday morning where bail will be opposed.