"It has spread its tentacles across New Zealand. We need to reduce demand to reduce supply, and we can't arrest our way out of this," he said.
Despite continual seizures of the drug in Northland, police said as recently as earlier this month they had seen no visible signs of an impact on its availability, as demand continued to grow and the price fell.
The latest Massey University Illicit Drug Monitoring Systems data showed a sharp rise in supply and declining prices in Auckland and Christchurch over 2015-16, a trend that authorities have also noticed in Northland.
District Police Commander Superintendent Russell Le Prou said the focus on seizing the drug had not had any visible impact on its availability.
The Massey University report revealed the average price of a gram of methamphetamine fell in Auckland from $579 in 2015 to $485 in 2016, and in Christchurch from $1002 to $746. According to police the price per gram fluctuates, depending on supply and demand, between $500 and $700, averaging $650, down from about $1000.
Superintendent Le Prou said concentrating on demand would take some time to produce change.