The Green Party has lodged a complaint with the Commerce Commission over the practice of gluing pieces of meat together and selling them as a single piece steak.
Greens consumer affairs spokesperson Sue Kedgley says media reports that it is becoming common for butchers to stick bits of beef together with meat glue called transglutaminase need to be investigated.
Ms Kedgley says consumers who would not want to eat glued pieces of meat may be eating it inadvertently in the absence of any requirement for labelling.
The MP says her complaint to the commission claims the practice breaches the Fair Trading Act by being misleading and deceptive. She believes there are also potential food safety concerns.
Ms Kedgley says consumers should be advised on a label, or by other means, that the meat they are going to eat has been glued together.
However, Beef and Lamb New Zealand is defending the long-standing practice.
Chief executive Rod Slater says the glue used in New Zealand purely in catering and restaurants to make pieces of meat the same size and is not scraps of meat stuck together as the Green Party claims.
Mr Slater says the practice is used particularly with eye fillet steak, which tends to be thick at one end and thin at the other. The two eye fillets are taken from a carcass and bonded together to make a steak that is the same thickness throughout.
Mr Slater says transglutaminase is a naturally occurring enzyme which in the animal's body helps to coagulate blood, hence its adhering properties.
He says it widely used in many areas of the food industry, such as in the making of bread, but not for meat sold in supermarkets and butchers.
However, Mr Slater believes it is a fair point that the customer has a right to know if meat has been joined in this way, but says it is up to the restaurant or caterer to tell people.
"Nobody's doing anything illegally; it's not contravening the Commerce Act ... and it's a practice that's been going on for a long, long time."
Mr Slater says the use of transglutaminase is not banned in Europe, as the Green Party has claimed, nor anwhere else.
The Commerce Commission says it will consider the complaint to see if there are grounds for an investigation.