South Africa's government has delayed the return to Cameroon this week of four endangered gorillas smuggled to Malaysia four years ago, the group organising the transfer said on Monday.
Cameroon has lobbied hard for the return of the young Western Lowland gorillas, dubbed the "Taipeng Four", who were shipped illegally to Malaysia's Taipeng Zoo in 2002 then sent two years later to South Africa, violating the Convention on International Trade in Endangered Species (CITES).
The four, who are at Pretoria zoo, had been due to be flown early on Wednesday to Cameroon, where their intended new home was the Limbe Wildlife Centre.
The International Fund for Animal Welfare (IFAW), which had agreed to fund the return of the animals to Cameroon, said South Africa's government had delayed the transfer.
"This eleventh hour decision to delay the return of the gorillas was entirely unexpected," IFAW's spokeswoman Christina Pretorius said in a statement sent to Reuters.
She added: "We understand that under the terms of CITES, South Africa, as the recipient state of the four gorillas that were confiscated in Malaysia, does not have the authority to re-export the animals".
She said South Africa was arguing that the final decision on where to place the animals rested with the authorities of Malaysia, the state where the apes were confiscated after it was found that their import documents were falsified.
Ofir Drori, director of the Last Great Ape Organisation, one of the groups lobbying for the gorillas' return to Cameroon, said diplomatic negotiations were taking place to ensure the transfer could eventually go ahead as soon as possible.
"We are patient and very certain that the gorillas will return to Cameroon," Drori said.
The fate of the great grey-brown apes, which weigh up to 275 kg (600 lb) and live deep within central Africa's tropical rainforests, has infuriated wildlife protection groups.
DNA sampling commissioned by Pretoria zoo established that Cameroon was the most likely place of origin of the gorillas.