A zoo in Australia was evacuated after an "ingenious" orangutan short-circuited an electric fence perimeter and hopped a wall surrounding her enclosure.

The ape, a 27-year-old female named Karta, jammed a number of sticks into wires connected to the fence and then piled up debris to climb a concrete and glass wall at the Adelaide Zoo.

Zoo curator Peter Whitehead told reporters Karta sat on top of the fence for about 30 minutes before apparently changing her mind about the escape and climbing back into the enclosure.

Karta came within a few meters of alarmed visitors, who were the first to notice the animal's escape bid. Whitehead said the animal was not aggressive, but the zoo was cleared as a precaution, and veterinarians stood by with tranquilizer guns in case of trouble.

(From another story) Zoo curator Paul Whitehead blamed Karta's escape on her intelligence.

"This animal has a history of trying to outsmart and be a little bit smarter and she's an animal which has caused lots of keepers a lot of late hours," he said.