Poachers have killed two male lions that were among more than 30 rescued from South American circuses and airlifted to South Africa.
The killing of the lions named Jose and Liso happened at the Emoya Big Cat Sanctuary, north of Johannesburg.
Animal Defenders International, a group involved in the lion transfer to South Africa last year, said that South African police and anti-poaching units are investigating.
The Emoya sanctuary said that it has increased security and the site is currently closed to visitors and volunteers.
In January, poachers cut through fences at another animal park in South Africa and decapitated and chopped the paws off three male lions, possibly for use in traditional healing rituals.
Nine lions were rescued from a circus in Colombia, and another 24 from circuses in Peru, and they were flown to South Africa in May last year.