Seven arrests have been made and $3.5 million in assets have been restrained as part of a 10-month operation by police.
Eighteen search warrants were executed this week as part of Operation Chestnut, described as a 10-month-long investigation led by the Manawatu Organised Crime Unit into the sale and supply of methamphetamine and associated offending in Tasman, Wellington, Central and Eastern police districts.
The first search warrant was carried out in Wellington on Wednesday, leading to the arrest of a 44-year-old man from Horowhenua with links to members of the Filthy Few, Hells Angels, Black Power and Mongrel Mob.
"He has been charged with 12 offences including possession of methamphetamine for supply, conspiring to deal methamphetamine, unlawful possession of a firearm, unlawful possession of a restricted weapon and money laundering," police say.
"He is scheduled to reappear in Wellington District Court on Thursday, November 4."
Warrants were also executed in Horowhenua, Himatangi, Horopito, Marlborough Sounds and Wellington on Thursday.
"In Horowhenua a significant cannabis grow was located with 60 mature plants and 4kg of packaged cannabis. The ready-to-sell cannabis is estimated to be worth about $40,000.
"Three Tasman men - aged 44, 50, 53 - have been charged with drug-related offending, alongside a 36-year-old man, 54-year-old man and a 53-year-old woman from Horowhenua.
"Assets totalling around $3.5 million have been restrained under the Criminal Proceeds (Recovery) Act."
The assets include six properties, a catamaran, a yacht, a leisure boat, a jet ski, a motorbike and classic cars. Nineteen firearms, methamphetamine and about $500,000 in cash were also seized.
Detective Inspector Paul Baskett says the long-running operation reflects police's commitment to disrupting and dismantling drug networks.
"This was a complex network involving a number of people in a range of situations and locations throughout the central and lower North Island and upper South Island.
"This type of offending undermines the wellbeing of our communities creating significant social harm.
"Police will continue to target those who illegally accumulate assets and wealth through the sale of illicit drugs.
"We want to help build resilient communities that thrive in the absence of illicit drugs and drug-related offending."
Police encourage anyone with information about suspected drug dealing in their community to contact 105, or Crime Stoppers anonymously via 0800 555 111.