Koko, the talented gorilla who mastered the art of sign language, has died aged 46

Koko, the gorilla who mastered the art of sign language, raised kittens and once cuddled with late actor Robin Williams, has died aged 46.

The Gorilla Foundation said that the western lowland gorilla passed away in her sleep at their preserve in California's Santa Cruz mountains on Tuesday.

Koko's talents with language and her ability to empathise inspired many.

She had appeared in many documentaries during her lifetime, and had graced the cover of National Geographic.

It is thought that Koko cound understand around 2,000 words of spoken English, and could use 1,000 signs to convey her feelings.