Under Operation Havana, Police and Customs have been investigating a syndicate using a method of allegedly importing drugs through the international postal system.
The illegal operation, largely based in a south-east Auckland suburb, was disrupted this week with 17 search warrants carried out across the city in recent days.
Twelve arrests have been made, along with a seizure of a concoction of illicit substances and $500,000 in cash.
In the process, approximately $4 million in assets have also been restrained under the Criminal Proceeds (Recovery) Act.
Detective Inspector Tom Gollan said the National Organised Crime Group and Customs have been investigating Operation Havana since 2022.
Over that period, Customs seized numerous packages, which hid controlled drugs destined for Auckland addresses, predominately in the Flat Bush area.
The consignments varied in size and concealment method but typically weighed between one and 10 kilograms.
"These characteristics, in particular the large number of consignments imported, were hallmarks of what is known as the 'scattergun' method of drug smuggling," Detective Inspector Gollan said.
Customs seized a significant quantity of illegal drugs both in New Zealand and worked closely with law enforcement counterparts to seize drugs in the United States of America.
These seizures included 183.5 kilograms of methamphetamine, 29 litres of liquid methamphetamine, 35.8 kilograms of pseudoephedrine and 16.7 kilograms of MDMA.
The social harm of the seized crystallised methamphetamine would have been more than $200 million alone, Detective Inspector Gollan said.
"At various addresses searched this week, we have located around $500,000 in cash, as well as drugs.
"This includes two kilograms of cocaine, 350 grams of methamphetamine and four kilograms of ephedrine."
Police have also restrained assets belonging to the group, including two houses and three vehicles.
Nine men, aged between 34 and 54, and three women, aged 36, 37 and 38, have been arrested.
Detective Inspector Gollan said an array of serious charges have been laid, including importing class A, B and C controlled drugs, conspiracy to import Class A and participation in an organised criminal group.
All 12 have appeared in the Auckland District Court.
Information sharing with a joint task force consisting of Homeland Security Investigations (HSI), Federal Bureau of Investigation (FBI) and Drug Enforcement Administration (DEA) special agents based in Los Angeles has been pivotal in the investigation, Detective Inspector Gollan said.
Information shared has enabled numerous arrests and the seizure of significant amounts of drugs on the US side of the illegal operations, he said.
"The Havana investigation exposed a syndicate that exploited the mail system to import their drugs over an extended period of time, and the arrests and significant seizures will put a significant dent in the supply of drugs by that group both here and in the USA.
"It again highlights the international flavour to our domestic illicit drug suppliers, and the value of our international partnerships to assist in combatting trans-national organised crime."
Police are not ruling out further arrests.
Customs Investigations Manager Dominic Adams said Operation Havana is another great example of domestic and international agencies working in close partnership, sharing intelligence and dismantling transnational organised crime groups operating in both New Zealand and the United States.
"Law enforcement is well-versed with criminal trends and it's not uncommon for Customs to find criminal syndicates using a scattergun approach to smuggle smaller packages of illicit drugs instead of a single larger shipment.
"These seizures add up to significant quantities, which is why Customs continues to target both small and large drug shipments at the border.
"Our frontline officers have been exceptional, diligently intercepting significant quantities of drugs before they reach our communities.
"Through the information collected, we've now been able to take down the New Zealand syndicate, while Customs and Police liaison officers based in Los Angeles were able to work with US authorities to tackle the overseas suppliers," Adams said.