South Africa's first online auction of rhino horn opened Wednesday, despite conservation groups protesting that the legal, domestic sale would encourage poachers.
The three-day selloff, organised by the owner of the world's largest rhino farm, kicked off after a last-minute legal tussle pushed it back two days.
"It has started," a representative of Pretoria-based Van's Auctioneers who declined to be named, told AFP after the auction website went live.
John Hume, who owns 1,500 rhinos on his farm north of Johannesburg, has stockpiled six tonnes of rhino horns and wants to sell 264 pieces weighing a total of 500 kilogrammes (1,100 pounds).
He harvests the horns by tranquilising the animals and cutting them off -- a technique he says is humane and wards off poachers.
Activists opposed to the sale fear it will fuel trafficking and undermine a 40-year global ban on the rhino trade.
"There is a strong likelihood that rhino horns sold domestically could be laundered into the black market and smuggled out of the country," TRAFFIC's wildlife trade specialist, Julian Rademeyer, told AFP.
He also said government agencies "simply don't have the capacity to regulate domestic trade" while police resources tracking poaching and smuggling networks are already over-stretched.
"It's hard to understand why anyone would buy rhino horn within South Africa when there are limited numbers of local consumers and it's still illegal to export rhino horn," said Jo Shaw of the WWF.
There was no comment from government following the opening of the auction, which comes after a South Africa's top court lifted an eight-year moratorium on the domestic trade of rhino horns in April.
A legal challenge delayed the auction for two days, but Hume was given a permit for the sale on Monday.
The auctioneers did not set an opening price for bids, but potential bidders need to pay 100,000 ($7,570) just to register and only registered bidders have access to the bidding process.
Environment Minister Edna Molewa had on Monday said the government was closing "any possible loopholes that could pave the way for a circumvention of (international) regulations".
An audit of existing rhino horn stockpiles was underway to "prevent the smuggling of illegally-obtained horns out of the country", she said.
Private rhino owners say so-called "blood horns" from poaching will not enter the market, as each horn is micro-chipped and their origins can be DNA-traced.
Breeders believe open trade is the only way to stop poachers from slaughtering the endangered animals.
They argue that the auction helps to promote "sustainable" use of resources and raise funds for protecting and conserving the rhino.
South Africa is home to around 20,000 rhinos, about 80 percent of the worldwide population, but in recent years the country has suffered record slaughter by poachers.
More than 7,100 rhinos have been killed by poachers in Africa over the past decade.
Rhino horns are highly prized in Asia, where they are estimated to fetch up to $60,000 (50,000 euros) per kilo ($27,250. 22,700 euros a pound) on the black market, exceeding the price of gold or cocaine.
The horns consist mainly of keratin, the same component as in human nails, and are sold in powdered form as a supposed cure for cancer and other diseases -- as well as a purported aphrodisiac -- in Vietnam and China.
Commodity speculators would be able to buy "but may not export the horns," Pelham Jones, chairman of the Private Rhino Owners Association, told AFP.
Any registered buyer will not collect the horns until they obtain special government permits, none of which have yet been issued.