Beeld reported on Wednesday that the vultures died after poachers killed an elephant and smeared poison on the carcass in Zimbabwe's Gona re Zhou National Park.
Andre Botha, a spokesperson for the Endangered Wildlife Trust, told the newspaper on Tuesday that poisoned vultures could end up breeding in the Kruger Park.
Botha said the disturbing new poisoning trend had originated in East Africa, where poaching had spiralled out of control.
The poachers poison vultures because they alert nature conservation authorities to the presence of a fresh carcass, and therefore the whereabouts of the criminals.
Botha warned that it was only a matter of time before the trend filtered across the South African border.
He said he had heard about the incident in the Gona re Zhou National Park from Professor Peter Mundy of the University of Bulawayo. – Sapa