Tip-offs from the community about suspicious behaviour led to police uncovering four commercial methamphetamine labs at the Waikato.
Waikato Police searched five addresses in Matamata, Waharoa and Morrinsville at the weekend and seized methamphetamine and large quantities of methamphetamine precursor chemicals and equipment.
Three men and one woman, aged between 35 and 59, have been arrested on charges relating to manufacturing methamphetamine and supplying methamphetamine and will reappear at Hamilton District Court either late this month or next month.
Waikato Police detective inspector Graham Pitkethley said police identified the ring with the help of the community who noticed suspicious behaviour.
"It is not lost on our communities that methamphetamine use has the greatest impact on our most vulnerable and we need to work in partnership to disrupt this type of offending."
The information provided about unusual or suspicious behaviour such as the comings and goings of vehicles at unusual times, chemical odours or the presence of security cameras assisted police to build a comprehensive picture about the manufacture, distribution and supply of drugs, he said.
"These labs are extremely dangerous and we would always encourage people to advise us of their suspicions without doing their own detective work."
Anyone with information about drug offending, suspicious financial activities or the identification and location of proceeds of crime is urged to contact police by phoning 105, or anonymously via Crimestoppers on 0800 555 111.