Between 30 and 40 people were buried by a landslide in southwest China on Wednesday, local officials said, as heavy rains in the area also destroyed homes and bridges.

The landslide in Zhongxing, in the southwestern province of Sichuan, was triggered by rain, the fire brigade of the provincial capital Chengdu said on its verified microblog account.

A Zhongxing official told AFP by phone that "so far we only know 11 families were buried and more than 200 residents have been evacuated", but that workers were still searching for others.

Much of China has been hit by heavy rainfall in recent days, including most of Sichuan, where three bridges have collapsed since Monday.

More than 2,700 rescuers were deployed to search for 12 people missing after a bridge in Jiangyou fell down on Tuesday, local officials said.

Accounts varied over the number of vehicles that disappeared in that incident.

Lin Rui, who was driving a minivan across the bridge and swam to safety through a torrential river, said there were 15 to 18 vehicles on the structure at the time.

"There were several cars ahead of me," he told state broadcaster CCTV. "A bus or a coach, I can't remember clearly, was running ahead."

Local authorities have said six vehicles were missing and denied any busses or coaches fell into the water.

Altogether downpours have destroyed 300 homes in Sichuan and neighbouring Yunnan, the state news agency Xinhua said, and about 36,800 people have been relocated.

Several major rivers were seeing "excessive water levels", the report said.

Mountainous areas in China's southwest are prone to landslides and earthquakes.

A landslide east of the Tibetan capital Lhasa buried 83 mine workers in April when it crushed their camp.

In January 46 people -- many of them children -- were killed in a landslide in Yunnan province, after more than 1,000 rescuers worked in freezing temperatures overnight in search of survivors.

China's deadliest natural disaster in three decades struck in Sichuan in 2008, when an earthquake left more than 80,000 people dead. Shoddy building construction was blamed for the high toll.