Teacher Tracey Devlin said it was obvious human intervention was the cause, but did not know if someone broke into the coup to set the six-week-old birds free or to take them home.

"They're angry that someone's done that and they're devastated because that was their project in terms of watching chickens grow and then using them as laying hens as part of our Kitchen Garden program," she said.

At first staff thought an animal may have got in, but Mrs Devlin said it was definitely the work of a human and not of a fox.

"The chicken-wire mesh that's on the side of the cage had actually been pulled or cut, it had been tampered with to get in."

Wollongong Police are investigating the matter though have no leads as yet. The missing fowls are described as 27-29 centimetres tall; four of them white in colour, three brown and two black. They may or may not answer to their names Eagle, Bark, Ghost, Goldie, Speckle, Shadow, Whitey, Nimbus and Feather.

Anyone with information should notify police, or the school.