The International Fund for Animal Welfare (IFAW) joined a chorus of other animal rights organisations who demanded the return of the animals, dubbed the "Taiping Four" to a wildlife centre in the west African country.

The gorillas arrived in South Africa last week from the Taiping Zoo in Malaysia after a journey lasting more than two years following their initial capture in Cameroon, where their parents were slaughtered for "bush-meat" (including meat from gorillas and monkeys.)

Smuggled out of Nigeria on false documentation, they ended up in Kuala Lumpur where the irregularity was discovered, said IFAW spokeswoman Christina Pretorius.

A Pretoria zoo filed an application to host the primates and was successful, receiving the animals on April 14.

Animal welfare organisations said the gorillas should be returned to their country of origin in accordance with the Convention on International Trade in Endangered Species (CITES) regulations.

"CITES says that where the country of origin desires the return of the animals, this desire should be respected," she told AFP.

Pretorius said the gorillas should be returned to the Limbe Wildlife Centre in Cameroon, which had requested the animals' return, but Willie Labuschagne, the zoo's executive director, disagreed.

"It has been agreed that the gorillas would partake in an international breeding programme in an attempt to secure the future of this highly endangered species," he said in a statement.

"Hundreds of gorillas are killed every year and if this continues, the last remaining gorilla in the wild will be killed in 10 years from now," he said.

Labuschagne has said previously that the zoo was a better suited facility to keep the animals.

"The National Zoological Gardens (in Pretoria) is, weight by weight, far more advanced and professional than the Limbe Wildlife Centre. It is really not comparing apples with apples," he told AFP previously.

TERRA.WIRE