SHANGHAI, CHINA - SHANGHAI officials have begun emergency flood drainage measures after waters rose past the city's flood defence warning level, state media reported.

Flood control authorities opened sewage pipes in three districts to cope with a combination of heavy rain, tidal flows and flood water released from nearby Lake Taihu, the Shanghai Daily reported on Wednesday.

The water level rose 20 centimetres above the warning level on Tuesday in an eastern part of the city after 27 millimetres of rain fell, the report said, citing flood control officials.

More rain is expected on Friday, it said.

Continuous rain has pushed the water level in Lake Taihu in eastern Jiangsu province to 30 centimetres above warning levels.

Lake authorities have started emergency drainage that feeds into the Huangpu River, which flows through the centre of Shanghai, the report said.

Heavy rain in southern China prompted the evacaution of more than 1.7 million people last week as water levels in the Pearl River Delta surged in some places to their highest levels in 50 years.

Officials also warned that the north could fall victim to the weather, and the government has urged dykes and reservoirs to be reinforced along the Yellow River, home to millions of urban and rural people. -- AFP