The free-range egg, poultry and pork industries are particularly vulnerable to the deceptive practices, says a report released yesterday by the Humane Society International.

"Bred free range", "eco-shelter" and "cage-free" were some of the terms creeping onto labelling for mainstream produce, with processors and manufacturers relying on lax labelling laws and consumer confusion to remain immune from prosecution under trade practice laws.

"Consumers want, and have the right, to make informed decisions about the animal-derived food products that they are purchasing," said the society's director, Verna Simpson. "Instead, they are met with a suite of confusing, poorly defined and unregulated terms which producers are able to use and misuse at will."

The society's survey of more than 3000 Australian consumers found that more than 93 per cent did not know that the label "bred free-range" meant the meat came from an animal that had access to the outdoors only in the first few weeks of its life, before being transferred into a factory-farming operation.

All but 2 per cent of those surveyed were unaware that claims that pork, chicken or eggs had come from an animal housed in an "eco-shelter" meant the animal had no outdoor access for its entire life. Even the terms "free-range" and "cage-free" were not particularly well understood, the survey found.

The NSW Greens MP John Kaye said the report showed food industry self-regulation of labelling was not working.

"The relationship of trust between farmers and consumers is being damaged," Dr Kaye said.