South Africa could ban rhino trophy hunting if other efforts to curb poaching fail, the environment minister said Wednesday.

"The minister of water and environmental affairs reserves the right to institute a moratorium if there is a clear abuse or absolute collapse in any of the provincial permitting systems," Minister Edna Molewa said in a statement.

At the moment "all rhino hunts must take place under the supervision of a conservation official or an environmental management inspector," according to the statement.

Rhino poaching has increased drastically in South Africa in the last years, on demand from the Asian black market to use the horns in traditional medicines to treat anything from fevers to cancer.

South Africa lost 333 rhinos to poaching last year and has lost 324 so far this year, up from 13 in 2007.

Black rhinoceros are threatened with extinction, but white rhinos -- which number 17,000 in South Africa -- can be hunted legally at only 50 rands ($6, 5 euros) a permit.

On Tuesday two white rhinos were found shot dead by poachers in the world-famous Kruger National Park.

The possible ban is just one proposal under consideration. At the other extreme, South Africa is also studying the legalisation of trade in the horns.