Two men have been charged after large quantities of class C drug ketamine were imported.
In a joint operation with Customs, police seized about 11 kilograms of ketamine as well as quantities of MDMA ecstasy in Wellington and Kāpiti.
Police searched six properties in those regions before arresting and charging a 19-year-old man and a 20-year-old man.
Charges include importing a class C controlled drug and possession for supply of a class B controlled drug.
Police said their investigation started after Customs noticed an increase in ketamine seizures across the Wellington and Kāpiti Coast regions.
In some cases, it was believed the drugs were imported in packaging masked as anti-inflammatory medication, police said.
They believe the offending uncovered in the operation happened between June 2022 and October this year.
Detective Senior Sergeant Hamish Blackburn said authorities were continuing inquiries into identifying the supplier responsible for exporting the ketamine to New Zealand.
"Police and Customs are committed to identifying and disrupting the importation of these types of drugs which target our communities.
"We are committed to holding offenders to account and delivering on our intent to keep New Zealanders safe."
Chief Customs officer for regional investigations Rachael Manning said authorities were always monitoring drug activity.
"Acting on intelligence that spans a global reach, we work closely with our police partners as well as our international law enforcement colleagues as needed to nab criminal operations like this one."