Three elephants trapped in a hilltop water storage tank in Yunnan province were finally freed on Tuesday, said Chinese state media.

Forest rangers found the elephants - a calf and two adults - on Sunday, but heavy rains filled up the 5m-deep tank and delayed rescue efforts.

The adult elephants, a male and a female, helped the calf stay afloat as the water rose, while other elephants roamed about the site, CCTV footage showed. Rescuers, who brought food for the animals, scared away nearby elephants with a helicopter and firecrackers before using an excavator to break down a wall of the tank.

The authorities believe the calf fell into the tank, used by local villagers to irrigate plants, and the two adults went in to help.

Around 300 Asian elephants are thought to inhabit China; most are in Yunnan, which borders Myanmar, Laos and Vietnam.