The 11 tigers kept at the Shenyang Forest Wild Animal Zoo, located in Liaoning Province's capital Shenyang, all died due to malnutrition, Shenyang Wild Animal Protection Station official Liu Xiaoqiang was quoted as saying by Xinhua News Agency.

He said the privately run, financially strapped zoo only fed the tigers cheap chicken bones, while it also kept them in excessively small cages in the wake of a mauling incident last November.

Two other Siberian tigers kept at the zoo were shot dead during the mauling incident, bringing the total number of tigers to have died there since then to 13. The zoo still has over 20 Siberian tigers left.

Liu lamented that China's Wild Animal Protection Law does not provide for any punishment for irresponsible zoo owners who abuse the animals, while the Property Law gives zoo owners the right to keep them without interferences from animal protection authorities.

The Siberian tiger, also known as the Amur tiger, is a subspecies of tiger which once ranged throughout western and central Asia and the Russian Far East, numbering in the thousands.

But it is estimated by the global conservation organization WWF that only 18-24 individuals remain in the wild in northeastern China and some 430-500 in adjacent areas of the Russian Far East.

But since China established a breeding base for the Siberian tigers in the number of captive tigers has increased from eight to more than 800.

WWF on Thursday released a technical report on potential tiger habitat in northeast China which concludes that vast tracts of natural forest still exist that tigers could re-colonize.

"Re-colonization of previously occupied tiger habitat in northeast China is a very real possibility if steps are taken to identify and manage these landscapes," Zhu Chunquan, conservation director of Operations, at WWF-China was quoted as saying in a statement.