Thousands of people living near a lake and a river in China's quake-hit southwestern province of Sichuan are being evacuated for fear of flooding.

The Qianjiang River has been blocked at many places by landslides caused by Monday's earthquake.

The water level in the Laoyingyan section of the river has reached the danger level mark, officials in Beichuan County said.

'It hasn't burst yet, but we asked people to leave because we need to prepare for the worst,' a relief official said.

He said experts were conducting aerial surveys of the river Saturday and considering whether to blast the blockages to discharge the water.

Hundreds of rescuers and local residents were seen leaving Beichuan Saturday.

Soldiers are helping the old and injured people to move to safer areas.

Dozens of rescuers in Beichuan are still searching for survivors and disinfecting the area.

The disaster relief headquarter said at least 7,227 people have died in Beichuan after the earthquake.

Some 5,894 people are still missing.
Meanwhile, at the Hongguang Township in Qingchuan County, authorities are evacuating some 2,000 people downstream of the Qingzhu River amid fears of flooding.

The Sichuan land resources department has warned of flooding.

The aftershocks have also pushed the debris into the river, raising the water level, experts said.

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

In Qianjin Township, the floodwaters have already entered the town.

Experts said the embankment around the lake is weak and may burst open if an earthquake occurs.

'If the lake bursts, it could form at least a 40-km waterway, and the results will be grave,' he warned.