ESCAPE-obsessed monkeys used springy tree branches to catapult themselves over a five-metre electric fence to freedom.

(This story originally ran on our site in 2010. It has reappeared in our most popular list because it is being linked to from another site.)

The Japan Times said the trees were a little over 1.8-metres high and about 1.8-3 metres from the high-voltage wire fence at Kyoto University's primate research centre.

Nevertheless, a dozen monkeys used them to leap over the barrier.

"Their jumping power was greater than we thought," said Hirohisa Hirai, deputy head of the institute in Inuyama.

However, the monkeys seemed not to know what to do with their new-found liberty following Sunday's great escape.

Most of them were found hanging around the outside of the fence and at least five were lured back inside with peanuts.

The trees were cut short to prevent further flights.

Originally published as Escapee monkeys fly to freedom