Police can now immediately test and identify if an unknown substance is methamphetamine, cocaine or MDMA thanks to a new drug scanning tool.

Lumi will launch today following a six-month pilot in the hands of frontline police. The device can instantly identify with 95 per cent accuracy if a substance is meth, coke or MDMA – giving police a better idea as to what action to take.

Assistant Commissioner Lauano Sue Schwagler says people were more likely to disclose what they were carrying when they knew officers could test it.

"This meant the officer could then directly assess if they were more suitable for a warning, health referral or to go through the courts process."

"This allowed better-informed police discretion, showed that negative samples wouldn't require further evidential testing and reduced the need for an officer to bring a person back to the station for further questioning."

It also allows police to better identify harmful drug hotspots and trends, and help with planning to deploy resources to where they're needed most.

Lumi was co-designed by police and Environmental Science and Research, and 150 of the devices will be rolled out across New Zealand next month. If successful police will look at developing the Lumi to identify other substances.

"Lumi won't replace other drug and alcohol testing devices and is a practical addition to Police tools for reducing drugs harm in New Zealand."