Koko the gorilla dies aged 46

Koko the - gorilla who mastered a version of American Sign Language - has died.

The 46-year-old passed away in her sleep at her home in California on Wednesday morning (local time).

"Koko touched the lives of millions as an ambassador for all gorillas and an icon for interspecies communication and empathy. She was beloved and will be deeply missed," the Gorilla Foundation in California said in a press release.

According to the Gorilla Foundation Koko was born at the San Francisco Zoo in 1971, and animal psychologist Dr Francine Patterson began teaching her sign language just a year later.

She was able to use more than 1000 hand signs, and also adopted a kitten.

However the tail-less tabby cat named All Ball escaped and was killed by a car in 1984. At the time Dr Patterson said she displayed grief for the loss of her pet.