Manufacturers and distributors of synthetic cannabis could face life in prison after the New Zealand government announced a crackdown on the drug following more than 50 deaths this year.

Active chemicals in the drug would now be classified as class-A drugs, health minister David Clarke said, and police would be given greater enforcement powers.

Synthetic cannabis is New Zealand’s most deadly narcotic, and bad batches of the cheap, potent drug have caused mass overdoses and a record number of deaths around the country.

Children as young as 11 are using the drug and entire neighbourhoods have collapsed under the strain of addiction.

Clarke said while the government would show zero tolerance towards those making and selling the drug, which was disproportionately consumed by the country’s most vulnerable and deprived people, police would be instructed to show “compassion” to users. Prosecutions would only go ahead if they were in the public interest.

The instruction to use “discretion” would apply to users of all illegal drugs, the health minister said, in a move the opposition party slammed as “legalisation by stealth”.

“We don’t want our jails full of people with addiction problems, we want those people getting treatment,” said police minister Stuart Nash.

“We are striking a balance between discouraging drug use and recognising that many people using drugs need support from the health system.”

Addiction services would also recieve a NZ$16.6m funding boost.

The drug reforms were applauded by the Drug Foundation who said the government had finally listened to those working in the sector, who said users need to be treated with kindness and recieve help treating their addictions, and social or mental health problems.

“The government is willing to confront the consequences of failed punitive approaches to drug harm and instead explore new and compassionate ways to address this public health emergency,” said Ross Bell, Drug Foundation executive director.

However the Police Association said it was concerned the government was asking frontline police to “spearhead” moves towards the decriminalisation of drugs, and though police supported helping rather than prosecuting addicts, treatment services were overwhelmed and officers were being asked to work outside their remit.

Synthetic cannabis is officially known as “new psychoactive substances” and the drugs imitate the effects of THC, the active ingredient in cannabis, but can be up to 50 times stronger.