A tiny koala that could fit into the palm of an adult's hand has become the star attraction at a Sydney zoo after staff nursed him back from the brink of death.

Zookeeper Darrelyn Rainey kept the prematurely born marsupial named "Koori" beside her bed, feeding him every two hours for two weeks after he was rescued from his mother's pouch last month.

Rainey said zoo staff had been very concerned about Koori's chances of survival.

"(It was a) two-hourly vigil for the first two weeks and now it's eased off and he's got into a good feeding pattern and he seems to be doing quite well," she told Reuters Television Wednesday.

Seven-month-old Koori weighed just 330 grams (11 ounces) and was in danger of being rejected by his real mother when he was given to his surrogate human mother.

He was extremely dehydrated, underweight and suffering from an infection common to koalas but has since put on an extra 40 grams and has become a boisterous joey.

Koori delighted staff when he took a few nibbles of gum (Eucalyptus) leaves, the koalas' staple diet. He will soon be weaned from his diet of specially formulated koala milk so he can rejoin his

See the sweet little koala here