Conservationists say 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 lions named José and Liso occurred 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 Saturday that South African police and anti-poaching units are investigating.
The Emoya sanctuary says it has increased security and that the site is currently closed to visitors and volunteers.
The conservationists did not provide details about the lion killings.
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.