"It would enable South Africa to have limited sales of white rhinoceros horns," said Phindile Makwakwa, a spokeswoman for the South African Department of Environmental Affairs and Tourism.

A final draft of the South African proposal is expected to be presented to the CITES Secretariat in June ahead of the next CITES' meeting in Chile in November.

Conservationists say the ban has stemmed the slaughter of the endangered animals, whose horns are prized for use as dagger handles in Yemen and as traditional medicines in southeast Asia.

South Africa maintains its population of white rhinoceros is healthy, growing and well-protected and that the cash raised will be used for conservation programmes.

On the brink of extinction a century ago, the southern African sub-species of white rhino was saved by conservation efforts in South Africa.

Its global population now stands at over 8,000, with most inhabiting South African game parks and reserves.

Animal welfare activists say lifting the ban would create a legal market that poachers could exploit to sell illegal horns.

"We see this as a global issue. We just don't see it as a matter of South Africa saying we have good enforcement measures in place," said Jason Bell, the director of the southern African branch of the International Fund for Animal Welfare.

"The bottom line is that many other countries don't have these measures and so their populations could be at risk...The people who deal in these products are unscrupulous," he said.

He added that lifting the ban could threaten rarer species of rhino, such as the black rhino of Africa and the great one-horned rhino of Asia.

Other controversial draft proposals being mooted by the South Africans include one to sell the stockpile of ivory from elephant tusks at the famed Kruger National Park.

The 1989 ban on ivory sales is credited with halting widespread poaching of Africa's elephants.

Conservationists say recent "one-off" ivory auctions by Namibia, Botswana and Zimbabwe have led to more poaching by criminals intent on laundering "dirty ivory".