Law enforcement is not a silver bullet for the country's methamphetamine problem.

A report by Police on arrestees has found an increase in the number of people who had used the drug, and felt dependent on it.

Executive director Ross Bell said lots of resources have been put into using police and courts to tackle meth use.

"We've kind of neglected for a long time putting resources into the health side of things, and I think now we're all beginning to recognise that we're never going to arrest our way out of the methamphetamine problem."

In contrast, the statistics also showed a reduction in use of alcohol and cannabis by those arrested, and it is thought that could be down to a change in police practice.

The study found 69 percent of detainees reported using cannabis in 2015 - that's down seven percent from 2011.

The number of detainees who reported being dependent on alcohol declined from 23 percent in 2011 to 17 percent last year.

Ross Bell said there's not a lot of data to successfully draw trends.

"The cannabis and the alcohol data could well be down to different ways that Police might deal with people - they may not actually arrest people for cannabis and alcohol."