Steven Reece Galbraith, left, and Tipu Huki Moetu, appearing in court for sentencing on charges for importing 500 grams of AMB-Fubinaca.

In one of the first prosecutions of its kind, two men have been sentenced to home detention for importing a deadly psychoactive chemical that could have made synthetic cannabis with a street value of half a million dollars.

A sting by Customs and police caught Tipa Huki Moetu, 32, and Steven Reece Galbraith, 30, both from Christchurch, bringing 500 grams of AMB-Fubinaca into the country earlier this year.

The "ultra-potent zombie drug" has been linked to about 20 deaths in the North Island in recent months – prompting warnings from the Chief Coroner and police. Medical journals claim it is 85 times as potent as THC, the active ingredient in cannabis.

CHRIS SKELTON/STUFF Synthetic cannabis has claimed at least 20 lives in New Zealand.

In the Christchurch District Court on Tuesday, Moetu and Galbraith, a father of four, were sentenced to eight months and six months home detention respectively for importing the psychoactive substance and ordered to do 300 hours' community work.

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The case highlights a continuing frustration for frontline police staff, who believe the two year maximum penalty for manufacturing, supplying or importing psychoactive substances, like those used to make synthetic cannabis, is not tough enough to deter those who stand to make large amounts of money.

SUPPLIED A synthetic cannabis dealing window in Christchurch.

The penalty was introduced in 2014 under the Psychoactive Substances Act, which banned non-approved products.

After Tuesday's sentencing, new Police Minister Stuart Nash said the Government would review legislation around psychoactive substances "as a matter of priority".

"I strongly suspect that when the law was passed no one envisaged the level of harm these psychoactive substances were going to cause the community," he said.

SUPPLIED A package addressed to Galbraith, described as containing "organic pigment", was intercepted by the New Zealand Customs Service in Auckland.

"When bringing [methamphetamine] in carries [a sentence of] life [imprisonment] there certainly seems to be some inequity around that."

According to the police summary of facts, Customs intercepted a parcel – addressed to Galbraith and described as containing "organic pigment" – at the International Mail Centre in Auckland on June 21.

Testing identified the contents as AMB-Fubinaca. A week later, staff from Customs and police completed a "controlled delivery" of the parcel – swapping out the drug with a placebo substance – to Galbraith's Christchurch home.

Galbraith then met up with Moetu and gave him the package.

Police confronted Moetu a short time later and found the package stuffed down the front of his jacket.

Its contents, according to police, could have made synthetic cannabis with a street value of up to $500,000.

"This importation was intended to facilitate large scale offending in relation to synthetic cannabis," Judge Alistair Garland said.

Last year a Stuff investigation revealed synthetic cannabis was a major driver of crime in Christchurch and was readily available online. The prevalence of the drug in the city earned it the name "Syn City" among people in the underworld.

At the time the issue, which then appeared to largely be confined to Christchurch, did not appear to be a high priority for policy makers.

Since then, there have been a series of deaths linked to synthetic cannabis in the North Island, mainly in Auckland. According to police investigating, ESR testing has often revealed the presence of AMB-Fubinaca – referred to in media reports as "an ultra-potent zombie drug".

There have yet to be any deaths in Christchurch linked to synthetic cannabis, but the number of users presenting at Christchurch Hospital is increasing.

The hospital's emergency department clinical director, David Richards, said there had been a "small change" in the side effect profile of the synthetic drug in some patients, indicating there was a new substance, or ingredient around.

"Some people are showing increased agitation and confusion, and a few people have suffered seizures. We are also seeing cyclical vomiting from both natural cannabis and synthetic cannabinoid."

Police are also regularly arresting people dealing the drug.

Detective Senior Sergeant Jason Stewart said it was concerning to see people try to import the potentially deadly chemical into Christchurch.

"I'm hoping this will be a clear message to anyone else out there that's thinking about trying to get involved in this – there's a very good chance that they will get caught."

Massey University's 2010-16 New Zealand Arrestee Drug Use Monitoring report showed 90 per cent of arrestees in Christchurch last year believed they could get synthetic cannabis in less than an hour. More than 60 per cent said it was "very easy" to get. In Auckland, 64 per cent of detainees could get the drug in less than an hour.

The proportion of Christchurch Central detainees who felt dependent on synthetic cannabinoids increased from 24 per cent in 2013 to 47 per cent in 2016.

Stewart said while it might be easy for those who had contacts, it was "risky" for others who were being stood over or robbed of their money when they tried buying the drugs.

"We're certainly aware of incidents where people are almost lured somewhere to buy it and everything looks rosy through their social media scene but it certainly doesn't end that way when they arrive."

Synthetic cannabis was a "significant driver of crime" in Canterbury as addicts resorted to violence to feed their habit.

"There's a lot of people that are using it that don't have an available income so they have to get money or goods often through crime to pay for the purchase of it which obviously leads to our cars being broken into, our houses being burgled, dairy robberies – a whole gambit of crime."

Stewart said synthetic drugs were "inherently dangerous products".

"Anyone who is using them is playing Russian roulette with their health and potentially with their lives."