The tests by the University of Stellenbosch late last year, were made before a scandal broke out in Europe about horse meat labelled as beef that raised concerns worldwide.

"Our study confirms that the mislabelling of processed meats is commonplace in South Africa. [It] not only violates food labelling regulations but also poses economic, religious, ethical and health impacts," said Professor Louw Hoffman, of the university's department of animal sciences.

Soya, donkey, goat, water buffalo and plant material were found in up to 68% of the 139 minced meats, burger patties, delicatessen meats, sausages and dried meats tested by the university.

The contaminants were not listed as ingredients.

Pork and chicken were the most common fillers found in products that a buyer would not have assumed contained them.

Stricter food labelling laws came into effect in March last year, with information required on content, country of origin and allergens.

But there is no mandatory government testing of food sold in South Africa.

"Meat in South Africa is generally safe to consume. This is mainly about suppliers being honest about their products and South Africans learning more about food regulations."

He said extensive tests over two weeks of more than 100 samples had found no trace of horse meat. Horses are slaughtered for food legally in South Africa.

"There is absolutely nothing wrong with horse meat," the general manage of the SA Meat Processors' Association, Stoffel Matthis, said yesterday.

He said there are three abattoirs in the country that process horse meat, located in Free State and Gauteng.

There was no risk that horse meat would be sold as beef in South Africa, he said.

"It goes mostly into pet food, and is sent to game farms and zoos," said Matthis. He did not clarify which pet foods.

Agriculture Department spokesman Steven Ganare said South Africa had a small market for horse meat. He said the three abattoirs operating in this country were monitored by qualified meat inspectors, and that horse meat was used in a range of animal products.

Hoffman said horse meat can be identified by its darker colouring, course texture and sweeter taste.

South Africans are finding humour in learning of donkey meat being found in food. Here are some of the comments posted yesterday on Facebook and Twitter:

• Tjaart Kristofferson Fourie: "I am more interested in the chemicals used; meat is meat, just don't lie about it."

• Pieter Venter: "Goats . donkeys and water buffalo - would explain why we are all so stubborn in SA!"

• Ndumiso Langa: "Suddenly horse meat sounds better, Donkey!!!? Hell no. No wonder we becoming dummber and dummer."