But the Rhino Rescue Project has come up with a kinder, but equally radical proposal - injecting the prized horns with a parasiticide that is extremely toxic to humans.

Lorinda Hern, a spokesman for the Rhino Rescue Project, based at the Rhino and Lion Reserve, northwest of Johannesburg, yesterday described the proposed treatment at a press conference at the reserve.

"The treatment is for the benefit and improved health of the animal - but it is highly toxic to humans."

The parasiticide's primary target is ticks. It is injected into the rhino's horn.

She said symptoms of ingestion of small quantities of the parasiticide by humans included "severe nausea, vomiting, convulsions and nervous-system" disruption.

As the parasiticide is injected into the sedated animal, a bright pink dye is also infused. It does not seep through to the surface of the horn and does not change its appearance, but its presence is detectable by X-ray scanners.

DNA samples will be taken and the data added to the proposed national rhino database to assist in the prosecution of poachers.

Hi-tech GPS-tracking devices will be implanted in the rhino horn.

Hern said that she had consulted extensively with lawyers locally and internationally and was convinced the treatment was legal.

"We made very sure that what we are doing is legal," she said.

Hern said the parasiticide, developed by the Lion and Rhino Park's veterinarian, consisted of a "cocktail of legally registered" drugs that would not affect the health of wildlife such as oxpecker birds.

The treatment represented the best short-term solution to fighting poaching on private game farms and reserves, she said.

The cocktail will be available to private rhino owners on request.

Hern said that, as contaminated horn reached its target market, word would spread that it was toxic if ingested and that would reduce demand.

Yolan Friedmann, director of the Endangered Wildlife Trust, said she could not comment on the project until she knew the composition of the parasiticide.

Friedmann said that, if it were legally compliant, and studies proved that it did not have a negative effect on the rhino, or on other animals, it could be a good idea.

More than 330 rhinos were poached in this country last year; more than 280 rhino have been poached this year.