Sniffer dogs are being used to scour city apartment blocks for drugs.
The specially trained dogs are making regular patrols of common spaces in up to 80 Auckland apartment buildings, where body corporate committees have hired them from a private company.
But a tenants' advocacy group has questioned whether neighboring residents would be told if drugs were detected in their building - and the Privacy Commissioner has expressed concerns.
NZ Detector Dogs managing director Janet Williams said demand was "huge" and increasing since they began offering the service about five years ago.
"We don't have to advertise. It's all from word of mouth."
The dogs were only used in common areas, including passageways, and did not enter apartments. If they smelled drugs that information was passed to building managers, Williams said.
"It's similar to having a smoke alarm in a hallway. There's a risk, we need to maybe just find out where the smell is coming from and follow up. It's not about people smoking dope in their apartments, it's about P labs. It is protecting people's investment and the health and safety of the entire building."
If a lab was suspected the company recommended building managers call police, she said.
However, Tenants' Protection Association manager Helen Gatonyi questioned whose responsibility it was to contact police and inform other residents of a suspected P lab.
"I suspect a lot of people would not want to inform police because it's $50,000 to remediate."
A police spokesman said although there were exceptions, people were generally not legally required to report crime or suspicious activity.
"However, we certainly encourage anyone who observes this happening to report it."
Gatonyi also feared privacy could be breached, especially of the innocent.
Drug smells could enter buildings with non-residents or by wafting in from neighbouring apartments. And use of drugs shouldn't automatically be grounds for eviction, she said.
"The tenancy shouldn't be in jeopardy because they happen to be using P outside the apartment. That's a different matter, that's a criminal matter outside of their living conditions."
Privacy Commissioner John Edwards said he would be concerned about sniffer dogs being used randomly on people, but using them in common areas would not intrude on the privacy of any individual.
"But I would very much question the utility of that, and caution against taking inferences that any given individual might have been involved in illicit activity in those spaces on the basis of a canine sniff test."
Fiore on Hobson building manager Utsav Pathak said he used drug detector dogs twice a year. No drugs had been detected and no residents had complained about the practice, which was included in the resident rules.
"Everybody wants peace of mind. I'd say about 70 per cent of buildings in the city get it done."