"Just be careful out there," is the message Masterton Mayor Lyn Patterson has for drug users in her community after seven people in the Wairarapa were hospitalised with suspected fentanyl overdoses over the weekend.
Drug information website High Alert said the 12 people who were affected displayed the same symptoms as an opioid overdose after consuming a white powder sold as cocaine and methamphetamine.
Preliminary testing has indicated the presence of fentanyl or a fentanyl-type substance.
The synthetic opioid is much more potent than morphine and is rare in New Zealand's underground drug market.
Patterson told 1News it is "extremely concerning" the synthetic opioid is in her community.
"Our community needs to be aware and recognise that if they're taking substances there is a high chance at the moment that it may contain fentanyl and could have fatal consequences for them," she said.
"It's extremely dangerous and we don't want it in our region or New Zealand."
Patterson said the region's hospital was already at capacity with Covid-19 and flu cases, so the fentanyl overdoses were putting further pressure on the local health system.
"We don't want it. We don't need it," she said of fentanyl.
"Just be careful out there."
Detective Inspector Blair MacDonald said the discovery of powdered fentanyl in the country is a "significant concern" due to the harm it has caused overseas.
The manager of the national drug intelligence bureau said more than 60,000 people had lost their lives in the US last year due to a fentanyl overdose.
MacDonald added just one gram of pure powdered fentanyl is the equivalent of 20,000 safe doses of the drug.
"Police are now working urgently to determine the source of the drug, and its prevalence in the community."
MacDonald told RNZ he was confident the fentanyl had been imported and it was "highly likely" it had come from China as it was powdered.
He explained the licit supply of the synthetic opioid in New Zealand is typically in liquid form.
Organisation Know Your Stuff said in 2018 it had detected the controversial painkiller at an unnamed festival. The owner of the white powder thought it was heroin.
It was said then that it was the first time it had been detected in New Zealand's illicit drug market.