The government has ordered the immediate evacuation of people in danger areas as waters of 40 rivers nationwide exceeded warning levels.
"We have to limit the loss of life and property to the lowest extent possible," Hui said.
Aside from rivers in the south, flood warnings have also been raised along the Yellow River in the north.
The river has been nicknamed "China's sorrow" for its long history of deadly floods, although in recent years it has been under threat because of excessive damming and water extraction for irrigation projects.
State television has broadcast images of Chinese troops in boats rescuing stranded people, bailing water and filling sandbags to shore up dykes.
But reports say it is difficult to tell how widespread the government response has been so far.
China's rescue and relief resources have already been stretched by last month's deadly earthquake in Sichuan province, which has itself now been hit by the floods.
|The government says damage |
has already topped $1.5bn [AFP]
In Sichuan many earthquake survivors have been ordered to move from temporary shelters amid fears that rains could trigger mudslides in terrain weakened by the quake.
One of the provinces worst affected by the floods is Guangdong – a major centre for export manufacturing which borders Hong Kong.
Parts of the major urban centres of Guangzhou and Shenzhen have been submerged by flooding.
Most of the damage so far has been to agricultural areas, with the impact already in local markets where the price of vegetables has gone up by as much as 70 per cent.
Chinese media says that economic losses across the flood zone amount to more than $1.5bn and are continuing to rise.