A zookeeper at Shanghai's zoo has been mauled to death by a rare South China tiger.

The keeper, known only as Mr Zhou (56), entered the enclosure to clean up but, said colleagues, "he did not come out again".

In a brief statement on Sina Weibo, China's Twitter-like microblog, the zoo said that investigators were looking into the cause of the incident. No further details were available.

The tiger was classified as a critically endangered species by the International Union for the Conservation of Nature in 1996. It is considered effectively extinct in the wild after decades of being hunted as a pest.

As one of the ten best ecological zoos in China, Shanghai's zoo is home to more than 600 species, including indigenous animals such as the giant panda and the golden monkey.

The American animal rights organisation PETA (People for the Ethical Treatment of Animals) expressed its view on the tiger attack: "Keeping tigers in zoo cages gives people the warped idea that these animals are little more than cuddly kitties."

"But captivity does not extinguish all the genetic drives that tigers are meant to follow. Attacks by captive big cats on people—which occur with staggering regularity—illustrate the profound level of stress, anxiety and agitation these animals experience every day of their lives."

"Zoos cannot tame tigers, and captivity is a living hell for them. In captivity, they cannot engage in any of the activities that give their lives meaning. Is it any wonder that tigers seize opportunities to make their frustration and rage known?"