Police have seized a massive shipment of drugs in a record-breaking bust following a lengthy covert investigation. 

The Herald understands the police intercepted around 600kg of methamphetamine yesterday, which is the largest amount ever seized in New Zealand, following a lengthy covert investigation by the National Organised Crime Group. 

A spokesman for the police declined to comment but it's understood a press release will be issued in the near future. 

According to court documents, five men have been charged with participating in an organised criminal group and being in possession of methamphetamine on March 1. 

One man has been charged with conspiring to import the class A drug between January 1 and March 1. 

They were due to appear at Manukau District Court today but the hearings were rescheduled to another date because of Covid-related court staff shortages. 

The men are from locations all across Auckland, including Remuera, Māngere Bridge, Papatoetoe, Rānui and Wiri. They are aged between 27 and 36. 

The largest previous shipment of methamphetamine was the 501kg smuggled into New Zealand from a "mothership" off the coast of 90 Mile Beach in Northland in 2016. 

In 2019, there was another police investigation where 500kg was smuggled into Whakatāne and a Customs operation where 469kg was stopped at the border. 

For many years, the most methamphetamine, also known as P or ice, discovered in one shipment was 96kg hidden in the bottom of green paint tins in Operation Major in 2006. 

Now, 100kg or more is almost routine. 

Two decades after meth took hold here, wastewater data shows, New Zealand has failed to curb its devastating popularity. 

An estimated 1 per cent of the population collectively spend more than $500 million a year on the drug, fuelling a lucrative criminal trade, causing extensive social harm and putting enormous strain on communities.