Most of the victims from Tuesday's rains were swept away by floods in Nghe An, Ha Tinh, Quang Binh and Thua Thien Hue provinces, the National Steering Committee on Storm and Flood Control reported. Twenty-one people were missing.
About 100 to 300 millimetres of rain fell Tuesday in the region, bringing the rainfall since Thursday to nearly 1.3 metres in most areas there but with some parts of Ha Tinh and Nghe An provinces reporting up to two metres of rainfall, officials said. Rains subsided Wednesday, but floodwaters have continued to rise.
Nearly 200,000 houses have been submerged or destroyed and livestock has been killed, the committee said. Local broadcasts showed victims in isolated areas seeking refuge on their roofs and calling for help.
In response, the government has dispatched nearly 20,000 soldiers to the area.
Among the missing were 20 passengers on a bus that was swept away by the Lam River Monday. The bus had yet to be found.
Thousands of other vehicles were stranded on the flooded highway that links north and south Vietnam as many parts of the road were 0.2 to 1.5 metres under water.
More than 20 sections of the railway between Nghe An and Ha Tinh were submerged, and Vietnam Railway cancelled several trains. More than 3,000 passengers stranded at stations were moved to their destinations by road.
"We are not sure when we will be able to resume train operations, but we will start fixing the tracks as soon as the water subsides," said Nguyen Huu Tuyen, head of Vietnam Railway's transport business department, as some tracks were under as much as 8 metres of water.
The Vietnamese government and international organisations launched emergency appeals for donations to help flood victims.
The International Federation of Red Cross and Red Crescent Societies Tuesday appealed for $1.08 million to assist survivors.
It warned that conditions might worsen if Typhoon Megi affects Vietnam this week. The storm moved away Tuesday from the Philippines, where it killed at least 13 people, and was heading toward southern China.