Calls to reconsider New Zealand's approach to drug use have received the backing of Labour's Palmerston North MP.

Following the release of statistics showing the number of people imprisoned for minor drug offending, Iain Lees-Galloway has echoed calls that drug abuse should be treated as a health matter, not a criminal one.

"Offending related to drug use such as violence, theft, driving under the influence of drugs etcetera should of course be dealt with as criminal matters, but the substance abuse itself is symptomatic of addiction and matters that are better dealt with in the health system," the Labour associate health spokesman said.

His comments followed reports that hundreds of people were being locked up for petty drug offences that the Law Commission said should not exist.

Last year a Law Commission review of New Zealand's 35-year-old drug laws criticised the uneven and criminally focused approach to drug offending.

It also recommended a three-strikes system for minor offending, and legalising pipes and needles.

Ministry of Justice figures showed 548 people were imprisoned for possession of a methamphetamine utensil such as a pipe.

For possession of a cannabis utensil 737 people were sent to jail, 890 people were imprisoned for possession of cannabis and 341 for being found with methamphetamine.

Mr Lees-Galloway said it was clear the laws were failing.

"They probably cause more harm than good. We need to build a consensus around what the regulatory system for drugs should look like and it should be built on the premise that drug abuse is a health issue, not a justice issue.

"The Law Commission suggests making changes to the regulation of possession but not supply.

"One example of a jurisdiction that has gone much further than anyone in New Zealand is currently suggesting is Portugal. They have decriminalised possession of all drugs and used the freed-up resources to tackle the dealers and to provide better treatment. After 10 years the results are looking positive."

However, Justice Minister Judith Collins said all drug offending - no matter how minor - should be dealt with in the criminal justice system.

She said: "The Government relies on enforcement agencies such as police to make appropriate decisions on how to charge someone for their offending, and the judiciary to make appropriate sentencing decisions based on the circumstances of individual cases."

The Government had policies to ensure anyone requiring drug treatment received it, she said.

Mr Lees-Galloway said Mrs Collins' comments were "nothing but classic tough-on-criminals rhetoric".

"This debate requires us all to listen to one another, accept nuanced arguments and agree that this can't all be solved with soundbites."