Persistent downpours in China have resulted in floods and landslides leaving 199 people dead and another 123 missing.
Chinese President Hu Jintao has called for rescue efforts in response to the dyke breach in Jiangxi province.
Torrential rains have hit southern China continuously for ten days.
Authorities have already moved out 68,000 people from around the Changkai dyke in Jiangxi province.
The dyke collapsed after a swollen river burst its banks.
Water in a reservoir upstream from the dyke has now exceeded danger levels, threatening the thousands who had still not moved out of harm's way down below in Fuzhou city.
The floods have hit ten provinces and 2.4m residents have left their homes.
Economic losses are thought to be up to 42bn Yuan (€5bn).
The National Meteorological Centre warned that parts of south eastern and south western China would see persistent heavy rains over the next 24 hours.
In Jiangxi, more than 10,000 soldiers and civilians had been mobilised for rescue and relief work after the dyke collapse and authorities called for desperately needed tents and food for the displaced.
State television broadcast images of rescuers in Fuzhou rowing boats through its submerged streets to fetch people stranded in buildings.
Relief workers were also seen throwing ropes to stranded flood victims clinging desperately to submerged trees amid raging torrents and pulling them to safety.
Authorities in Fuzhou have set up 17 makeshift shelters for flood victims at stadiums and local schools.
Large flood-hit areas of southern and south western China, particularly Guizhou, Guangxi and Chongqing, had only just recently emerged from a crippling drought that was the worst in a century in some regions.
