Around 40 rhino horns worth millions of dollars have been stolen from the safe of a state tourism organisation in South Africa.
The horns - which are highly prized in some forms traditional medicine - were taken from the Mpumalanga Tourism and Parks Agency (MTPA) at the weekend, the Lowvelder newspaper reported.
"The culprit, or culprits, cut open two steel safes fitted with double locks," a source from the agency said.
Dex Kotze, conservationist and CEO of South African jeweller Jenna Clifford, which backs a campaign against rhino poaching, said the haul could be worth as much as $US16 million ($A17.1 million).
Neither the MTPA nor the police could be reached on Monday, a public holiday in South Africa.
Poaching of South African rhinos is on the rise, with more than 270 killed already this year, nearly half in the Kruger Park, despite the deployment of troops to protect them.
The horns are much sought after in parts of Asia, particularly in Vietnam, for use in traditional medicine, even though they are made of keratin, the same as human fingernails.
Poachers often kill the rhinos with semi-automatic rifles, hacking off the horns and leaving the animals wounded or dead.
South Africa is home to nearly 20,000 rhinos, which make up 70 to 80 per cent of the world's total rhino population.
Illegal hunting of the animal in South African parks continues despite air and foot patrols, as well as increased numbers of rangers assisted by soldiers.
