The shipment was sent from the United States in September. Photo: Supplied / NZ Police
More than 500kg of methamphetamine concealed in steel beams has been seized one of New Zealand's biggest importations of the drug.
Customs intelligence-gathering had flagged the shipment sent from the United States last month for further investigation, which uncovered inconsistencies in some of the 42 steel beams.
That led to the consignment being x-rayed by Customs officers and the discovery of the meth.
The shipment was then tracked to a rural Waikato address, which was raided by both agencies last on Friday in a joint Customs and Police operation.
Two men visiting from Australia were arrested in the process of deconstructing the beams, police said.
Three other men across Auckland and Waikato were also arrested.
The five men, aged between 31 and 51, appeared in the Auckland District Court on Friday facing charges relating to the importation and supply of methamphetamine.
One of these men has been charged with unlawful possession of firearms after a military-style semi-automatic rifle and ammunition were recovered.
The two men arrested in the Waikato on 4 October are New Zealand passport holders but live in Australia.
A military-style semi-automatic rifle and ammunition were recovered, police said. Photo: Supplied / NZ Police
Police said it was New Zealand's second largest importation of methamphetamine.
Detective Inspector Colin Parmenter, from the National Organised Crime Group, said the seizure was a significant disruption to the wider drug market operating within New Zealand.
"It's estimated that this shipment would have gone on to produce 25.7 million individual doses of this destructive drug, and preventing this harm is a key motivation for our staff."
Investigations would continue and further arrests could not be ruled out, he said.
Customs said its intelligence-gathering and targeting played a critical role in the operation.
"The method and scale of this smuggling operation clearly illustrate the amount of efforts organised crime groups are willing to go to but our seizure and the arrests Police have made equally show the skill and determination investigations and enforcement teams will apply to detect, disrupt and dismantle these criminal efforts," Terry Brown, Customs group manager intelligence, investigations and enforcement, said.