More than 20 people have been arrested following a series of coordinated drug raids.
Code named Operation Python, the operation involved more than 60 Police and Customs staff including detectives, dog handlers, public safety officers and members of police specialised units.
They were deployed to properties in Wellington, Porirua, Tawa, the Kapiti Coast and Hutt Valley over the past seven days targeting organised crime and drugs imported from the internet.
Twenty-nine search warrants were executed which led to the arrest of 21 people aged between 21 and 52.
Those arrested will be appearing before the courts on charges including serious drug dealing, receiving stolen property and possession of firearms.
The drugs seized included methamphetamine, cocaine, LSD, GBL, MDMA and cannabis.
At a Wellington address, police located a significant haul of stolen property, $20,000 worth of methamphetamine and a large number of samurai swords.
A house in Tawa valued at more than $300,000 was also restrained by police's Central Asset Recovery Unit.
Detective Inspector Darrin Thomson said the joint seizures of drugs and guns was concerning.
"At one address we found a cache of firearms that presents a real risk to police staff and the community."
During the course of the investigation, police worked closely with Customs and identified that there were people importing drugs through the internet including using the underground website Silk Road.
"Our message to those involved in using the internet for this purpose is that Customs and police are actively investigating this method and we will continue to take action where appropriate," Mr Thomson said.
"People may think it is somehow anonymous but we can assure you that this technique is being actively monitored.
"Over the past few days we have seen a number of people who would not fit the usual profile of a drug importer get themselves caught up in serious offending.
"This has had a devastating impact on their families."
Over the past seven years close to 600 arrests have been made, dozens of firearms and weapons have been taken off the streets and millions of dollars of assets restrained and drugs seized as a result of Operation Python.