The Panthera charity has described it as a "truly unique case"
Photos have been released appearing to show the first evidence of a wild lioness nursing a leopard cub.
The remarkable photographs were released by the Panthera charity, who were sent the images by KopeLion.
The pictures were captured at the Ngorongoro Conservation Area in Tanzania, and show a five-year-old lioness known as Nosikitok nursing a cub of a different big cat species.
The cub is estimated to be only around three-weeks-old.
The images - captured by Ndutu Lodge guest Joop Van Der Linde - can be seen in the below video:
Panthera President and Chief Conservation Officer Dr Luke Hunter said that it is a "truly unique case".
He explained: “I know of no other example of inter-species adoption or nursing like this among big cats in the wild. This lioness is known to have recently given birth to her own cubs, which is a critical factor.
"She is physiologically primed to take care of baby cats, and the little leopard fits the bill - it is almost exactly the age of her own cubs and physically very similar to them."
He suggested that the reasons for the encounter are still 'mystifying', but theorised that the lioness may have lost her own cubs - and therefore the bereavement may have made her "particularly vulnerable".
Dr Hunter warned that the cub faces a serious survival challenge, and would likely be killed if discovered by the rest of the lion pride.
However, he also predicted what would happen if the leopard survived: "Even its early exposure to lion society would not override the millions of years of evolution that has equipped the leopard to be a supreme solitary hunter.
"I am sure it would go its own way.”
In a Facebook comment, Ndutu Safari Lodge says the baby leopard "hasn't been seen again".
"There is a female leopard known to be living in this area so there is a small chance it was reunited with it's mother," the lodge adds.