Two AFL stars who failed drugs tests are looking to place the blame on NZ steak contaminated with the muscle-boosting drug clenbuterol while in Queenstown.

Josh Thomas and Lachie Keeffe

That suggestion has been dismissed by the meat industry in this country, however.

Collingwood pair Lachie Keeffe and Josh Thomas have tested positive to clenbuterol, threatening their careers and rocking the AFL with a fresh doping scandal.

Keeffe and Thomas tested positive on February 10, two days after the team returned from a Queenstown training camp.

The pair are under provisional suspension.

Their B samples will be tested on April 14, but this is expected to be a formality and they most likely will have to front the anti-doping tribunal.

They face the sack and up to a four-year ban.

Clenbuterol is sometimes used in the treatment of horses and to increase lean meat in cattle, and can be used to build muscle and increase aerobic capacity in humans.

Melbourne's Herald Sun newspaper has reported that Keeffe and Thomas' lawyers will investigate whether steak they ate at a New Zealand restaurant caused a positive test, although the club has privately dismissed the suggestion.

It is illegal to give clenbuterol to cattle in New Zealand.

"Let me tell you there's been no evidence of it in our history before, it's not something that's cropped up in New Zealand before," Bill Falconer, chairman of the Meat Industry Association of New Zealand, told 3AW in Melbourne.

"You can read stuff that there are rumours of it happening in China and in Spain, but no, not in New Zealand."

Clenbuterol is the banned substance that cost Spanish cycling ace Alberto Contador his 2010 Tour de France title because of a positive test.

Australian cycling star Michael Rogers also tested positive to clenbuterol, but was cleared on appeal.

Contador and Rogers had the same defence - that they ate contaminated meat.