At least eight people have lost their lives in devastating flash flooding that has ravaged parts of China, with four others still missing after two died at a recent beer festival.

The banks of a river running through the grasslands of Inner Mongolia burst at around 10pm on Saturday, washing away 13 campers on the outskirts of Bayannur, a key agricultural hub.

A search and rescue operation involving more than 700 people is underway, according to state news agency Xinhua. One person has been rescued.

Bayannur is an important national grain and oil production base, as well as a sheep breeding and processing centre.

China has faced weeks of extreme weather since July, with heavier-than-usual monsoon downpours stalling over the north and south of the country.