Melioidosis, a bacterial infection, was responsible for killing at least nine monkeys at a Hong Kong zoo, authorities said, as a further two died over the weekend, taking the total to 11 in the past week.

Hong Kong’s oldest zoo is seeking answers in a monkey medical mystery after nine animals died in two days, including three members of a critically endangered species.

STORY: At least 11 monkeys have died at this Hong Kong zoo over the past week.Authorities say they've now worked out why for at least nine of them - a soil infection. Two more died at the weekend and their cause of death has yet to be determined.

A 11th monkey from the Hong Kong Zoological and Botanical Gardens was found dead on Sunday whilst under quarantine, the government has said. In a statement issued on Sunday evening, the government said a common squirrel monkey died while being placed under isolated surveillance.