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."