A South African game reserve has developed a treatment for rhino horns that is safe for the animals but causes convulsions and headaches to people who consume them, a wildlife group said.

The potion is a mixture of drugs used to kill parasites on the rhinos, and includes a dye that turns even finely ground horns neon pink when seen by airport scanners, Rhino and Lion Reserve spokesman Lorinda Hern told national news agency Sapa.

“The chemicals have the dual threat of keeping away both natural and human parasites... and last for three to four years,” she said.

The treatment has been tested on rhinos at the park outside Johannesburg, she said.

“A permanent solution would be to eliminate the demand for rhino horn altogether,” said Ms Hern.

Since the beginning of the year, 279 rhinos had been killed for their horns at parks across the country according to the national parks agency.

Last month, the ministry of environmental affairs said it was investigating dehorning rhinos and stopping legal trophy hunts to fight poaching, which has seen the army being deployed to the Kruger National Park.

Poaching has soared from just 13 cases in 2007, an increase powered by demand for rhino horns in Asian traditional medicine.