Food safety regulators say they haven't seen any surge in illicit "backyard butchers" and over the past 12 months it has had just three complaints directly relating to the sale of home-killed meat.

"This is roughly consistent with previous years," said a spokesman for the New Zealand Food Safety Authority (NZFSA) after the rural butchers' arm of Federated Farmers called for the law to be enforced against black market backyard butchers suspected to be linked to livestock rustling.

Mike Hanson, chairman of the federation's rural butchers section criticised operators he described as untrained cowboys and called for more effort to be put into combating rustlers and backyard black market butchers with which he said they tended to work.

"I have little doubt that rustling, much of it unreported, is linked to organised crime because you need a fairly sophisticated operation," he said.

"The people who actively trade in black market meat are as guilty in my book as the people who steal farm animals," he said. "They need to be caught and punished as well."

Mr Hanson, an Ashburton retail butcher and a home-kill operator, said rural butchers wanted a concerted effort involving council environmental health inspectors, the NZFSA and police to enforce existing legislation.

But the NZFSA said that most cases of illegal slaughter it had investigated had not involved the theft of the live animal.

In addition to complaints from consumers, the NZFSA also investigates information received from sources such as quality assurance verification agents, and in total it completed investigations into 29 home kill operations in 2009, and 30 in 2008.

The authority had assisted police on three other cases involving rustling since its creation in 2002, but where people were stealing animals to eat, rather than retail the meat, it would not be the main agency.

In the past couple of years, it had mounted three prosecutions relating to illegal animal slaughter -- gaining sentences including imprisonment and significant fines -- and had considered two other prosecutions.

Prosecutions were only taken where there was no other sanction available, where offending was severe or repeated, or where there was no previous legal precedent.

In future, individual identification of animals with microchip tags would be useful to help trace livestock and carcasses -- but only to the point where the animal was butchered and divided among offenders.