91Èȱ¬

A lion has been spotted in Chad's Sena Oura National Park, where the big cats have not been seen since 2004 and were believed to be extinct until now.

A photo of a lioness was released by a team of conservationists from the Chad government and the New-York based Wildlife Conservation Society (WCS).

"The photo shows a prime, very healthy adult lioness, around five years old," WCS Big Cat Programme executive director Luke Hunter told the 91Èȱ¬.

"I am sure she is not alone," he said.

The image - taken by a remote camera in the protected area back in February - was released on Thursday.

"This is hugely encouraging because prime females are the foundation of any lion population, and they are not big wanderers: they inhabit areas that have prey and are safe to raise their cubs in," said Dr Hunter.

He added that her presence was an early sign of lions recovering in an adjacent national park in Cameroon.

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The WCS says that the region "saw a period of ruthless, organised poaching more than a decade ago, but has since benefitted from a very strong commitment to conservation by the governments of both Cameroon and Chad".

"This has produced better protection of the national parks and wildlife populations are now starting to recover," the organisation adds.

Dr Hunter says that there are about 22,000-24,000 lions left in the wild, the vast majority of which are classified as the southern lion sub-species native to east and southern Africa.

There are fewer than 1,000 northern lions in west and central Africa, and they are "especially endangered and precious", he adds.