Methamphetamine, a loaded shotgun and ammunition were seized today as police targeted a drug supply operation in Nelson and Marlborough.
Officers and the Armed Offenders Squad executed search warrants targeting gang associates, police said.
Tasman District Crime Services manager, Detective Inspector Mark Chenery, said: "As a result, a 55-year-old man will appear in the Nelson District Court today on charges including conspiring to deal methamphetamine and unlawful possession of a firearm.
"A 51-year-old man will appear in the Blenheim District Court tomorrow on multiple drug-related charges including possession of methamphetamine for supply."
Chenery said illicit drugs continued to cause "significant harm" and police had no tolerance for them being dealt.
The investigation was ongoing and further charges were likely, he said.