UPDATED 10.32am: John Key said a poll showing nearly two thirds of New Zealanders want cannabis legalised, doesn't convince him that making it legal would be a good idea.

The Prime Minister told Mike Hosking the government hasn't discussed it at great length but his view is clear.

"My longstanding view, whether you like it or not has been that I think it sends the wrong message to youngsters."

"I think there are potentially health implications from sustained use," he added."

He said people are unlikely to get prosecuted for small recreational use anyway.

Labour leader Andrew Little isn't keen on decriminalising it either.

Mr Little said it wouldn't be Labour policy to decriminalise it, and he also couldn't get behind it personally.

"When I was an employment lawyer dealing with a lot of workplace alcohol and drug testing cases, I saw a lot of scientific and medical information about the health risks of cannabis and I'm just not sure it can be something easily mitigated," he said.

A new poll suggests nearly two in every three New Zealanders want personal possession of cannabis decriminalised, or made legal.

There's even stronger support for allowing medical use of marijuana.

• Rachel Smalley: Cannabis isn't the big scary beast it once was

The polling was commissioned by the Drug Foundation.

A new poll shows almost 65 per cent of NZers want personal possession of cannabis decriminalised or made legal. pic.twitter.com/jEKwx04VHI

— NZ Drug Foundation (@nzdrug) August 14, 2016

Director Ross Bell said the results should embolden politicians as support for reform is now a majority position.

Labour's indicated it could hold a referendum on decriminalising cannabis and National will shortly review how harshly people are dealt with for low level drug offending.

However, the Drug Detection Agency argues people want to make money off cannabis, and that's why there's a move to legalise it.

TDDA founder Kirk Hardy said there's plenty of well-founded research against legalisation.

He told Rachel Smalley it's highly addictive and open to abuse.

LISTEN ABOVE: Kirk Hardy speaks to Rachel Smalley 

"When we're talking about cannabis, we're talking about a billion dollar industry a year. So there are a lot of people out there who are just waiting for this drug to be decriminalised or legalised so they can start opening up their hemp shops and smoke shops."

Kirk Hardy adds feedback from rehabilitation centres shows people don't know when they're hooked.