More than 2,000 people are being evacuated from around a lake that is threatening to burst in southwest China's earthquake zone, geological experts and soldiers said on Saturday.

Multiple landslides set off by the powerful earthquake blocked parts of the Qingzhu River in the Hongguang Township in the Qingchuan City, and formed a large stretch of water, which experts with the Sichuan land resources department said exceeded 10 million cubic meters.

More debris slides caused by aftershocks were likely to continue to push the water level up, experts said.

"If the water level rises by another two to three meters, it will overflow and threaten more than 2,000 people who are staying in shelters after the earthquake downstream," one of the experts said.

Water had already overflowed into the streets of a neighboring village in the Qianjin Township, he said.

Experts said the lake embankments were very loose after being shaken by the earthquake, which also heightened the risk of a burst.

"It the lake bursts, it will form at least a 40-kilometer waterway, and the result will be grave," he warned.

Earthquake disaster relief officials in Qingchuan have started to evacuate the people in downstream areas and consider to blast the embankment to divert the lake water.