An Australian zoo was evacuated after an "ingenious" orang-utan escaped from her enclosure by short-circuiting an electric fence today.

Staff at Adelaide zoo said 137lb (62kg) Karta used a stick to short-circuit the electric wires around her enclosure before piling up some more sticks to climb out.

But the 27-year-old ape only ventured as far as a surrounding fence, still metres from members of the public, during her 30 minutes of freedom.

The zoo's curator, Peter Whitehead, said she seemed to realise she was somewhere she was not supposed to be and returned to her enclosure.

"You're talking about an animal that's highly intelligent," he said.

"We've had issues with her before in normal day-to-day operations where she tries to outsmart the keepers. She's an ingenious animal."

Karta was spotted by a member of the public and, although she returned to her enclosure, the zoo was evacuated as a safety precaution.

Whitehead said the orang-utan was not aggressive and had not been close to members of the public.

However, vets stood by with tranquiliser guns in case of trouble.

Zoo officials will conduct a thorough review of Karta's escape attempt.