The Ministry for Primary Industries is issuing warnings both for people eating stolen meat, and the people stripping it from Northland cattle which have been shot and killed on the spot.
1 NEWS reported on Thursday about farmers saying they're prepared to turn to their guns to try to protect themselves.
It's amid what farmers say is a surge in cattle being shot, killed and butchered for meat.
Some photos shown to 1 NEWS show animals left decapitated.
The farmers told us they think they're at the centre of organised hits, with the stolen meat heading for the black market while beef prices are high.
"It's got to be going somewhere, they've got to be feeding somebody. I'd say it's going down to Auckland," farmer Bruce Clare said.
"We've heard whispers that there are outlets north of us that actually take this meat, probably buy it off these guys and then they process the meat," Snow Tane from Te Roroa Development told us.
Farmer Ian Russell said his meat has gone as far as Waikato.
Unregulated meat is a problem MPI is already grappling with, saying the ministry comes across what are often "sophisticated" operations.
"It is so tempting in difficult economic times to go for the cheap option, but the cheap option comes with significant risk.
"Is it worth putting your family in hospital for the sake of a meal? I don't think so," MPI Compliance Investigations manager Gary Orr told 1 NEWS.
He had a warning as well for the people killing and stripping the cattle.
"We'll prosecute if we can get the evidence to support a prosecution. It's a high priority for us because the public's health is at risk, and we don't want anybody getting sick," he said.
Beef + Lamb NZ said it's hard to say how extensive the stolen meat problem is, but called it despicable.
"We totally condemn this behaviour. It's criminal, and what sort of low-life person wants to go around shooting animals in a paddock and leaving them there to die?
"It's beyond rational, to be frank," Rod Slater, Beef + Lamb NZ chief executive, said.
Mr Slater said Beef + Lamb NZ wasn't aware of any organised supply chain working in the Auckland area, and said reputable retailers wouldn't touch such meat.
MPI advises butchers, retailers to check sources
New Zealand Food Safety takes reports of unregulated or "black market" meat very seriously. The selling and buying of meat obtained outside of the regulated system is illegal, and punishable with fines and prison terms.
There are checks and balances to prevent unregulated meat from reaching consumers. Compliance and record-keeping is required through both the Animal Products Act and Food Act at all levels for meat processing.
These systems ensure that meat purchased from butchers and supermarkets is safe to eat and obtained legally.
Our advice to butchers and retailers is that they check their sources' registered information thoroughly so they can be certain the meat they sell is safe to eat.
We encourage people to contact New Zealand Food Safety if they suspect the meat they purchased is from a disreputable source. Our number is 0800 00 83 33.