Floodwaters surging through Himalayan foothills in western China have swept bridges, houses and hillsides into roiling brown torrents, leaving at least 31 people dead and 166 missing Thursday, as heavy rains buffeted many parts of the country.

Flooding in the western province of Sichuan was the worst in 50 years for some areas, with more than 220,000 people forced to evacuate.

Nationwide, at least 46 people have died due to the violent weather since Sunday, according to figures from the Ministry of Civil Affairs and the official Xinhua News Agency. Thousands of homes have been destroyed or damaged and transportation has come to a virtual standstill in hard-hit areas.

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Many of the casualties in Sichuan were from a massive landslide that struck a scenic resort outside the city of Dujiangyan, killing 18 people and leaving 107 missing. An entire hillside collapsed onto clusters of holiday cottages where city dwellers escape summer heat, a survivor told Xinhua.

"The noise was like thunder and went on for two or three minutes. My first thought was that I too would be buried," Gao Quanshi, 47, was quoted as saying. Phone lines were cut, so villagers had to trek to nearby government offices to call for help, he said.

Images from the scene showed a valley filled with mud and rocks, with only the tops of trees sticking through. Drenched rescuers wearing helmets and life jackets worked mostly with hand tools to prevent harming any survivors still trapped beneath.

A total of 352 tourists had been rescued from the area as of Wednesday night, Xinhua said. Overall in Sichuan, there were at least 31 people dead and 166 missing, said the provincial department of civil affairs.

A mudslide in Sichuan's Aba prefecture left three people dead and 12 others missing, Xinhua said.

Mudslides and flooding are common in China's mountainous areas, killing hundreds of people every year, but in some areas the current floods are already the worst in half a century. Reports said the 94 centimetres of rainfall that fell on Dujiangyan over 40 hours beginning Monday was the heaviest since records began being kept in 1954.

2,000 people rescued

Also in the west, more than 2,000 people were rescued after being trapped for several hours Wednesday in a highway tunnel between Dujiangyan and Wenchuan — the epicenter of the Sichuan earthquake five years ago that left 90,000 people dead or missing.

Across China at least 1.6 million people have been affected and thousands of homes damaged, by flooding and landslides since Sunday, according to the Ministry of Civil Affairs. (Reuters)

Bridges have been closed and train service suspended in some parts of the province.

In nearby Beichuan county, flooding destroyed buildings and wrecked exhibits at a memorial for earthquake victims.

The flooding also caused the collapse of an almost 50-year-old bridge in a neighboring county, sending six vehicles into the raging waters and leaving 12 people missing.

The region lies in the foothills of the Tibetan Plateau, where mountains rise sharply from the densely populated Sichuan basin. Fast-running rivers quickly overflowed their banks, flooding scores of towns and parts of the provincial capital of Chengdu, where the waters rose to the second floor and covered the tops of cars.

In Chengdu, stone bridges and brick houses along river banks were swept away, including one in which the residents were taking shelter, while others crumbled into the saturated earth already rent with fissures from the magnitude-8.9 2008 earthquake.

In the northern province of Shanxi, at least 12 workers were killed Tuesday when a violent rainstorm caused the collapse of an unfinished coal mine workshop they were building.

Another three people were drowned in a car in Hebei province outside the capital, while an additional 11 people were reported dead or missing in Yunnan province, Beijing, Inner Mongolia and Gansu province.