Floods caused by a tropical depression in Vietnam killed 37 people, one of the highest death tolls recorded in the country from flooding, the disaster prevention agency said on Thursday.

Forty people were missing and 21 others were injured after rains caused landslides and flooding, mostly in northern and central Vietnam.

"Our entire village had sleepless nights...it's impossible to fight against this water, it's the strongest in years," Ngo Thi Su, a resident in northwestern Hoa Binh province, was quoted as saying by state-run Vietnam Television (VTV).

Vietnam often suffers from destructive storms and floods due to its long coastline. More than 200 people were killed in storms last year.

A typhoon tore a destructive path across central Vietnam just last month, flooding and damaging homes and knocking out power lines.

The latest floods hit Vietnam on Monday.

Vietnam's Central Steering Committee for Natural Disaster Prevention and Control said authorities were discharging water from dams to control water levels.

In a report, it said more than 17,000 households have been evacuated and more than 200 homes have collapsed, while nearly 18,000 other houses were submerged or damaged.

It said more than 8,000 hectares of land growing rice was damaged and around 40,000 animals were killed or washed away.

Hoa Binh province in the northwest declared a state of emergency and opened eight gates to discharge water at Hoa Binh dam, Vietnam's largest hydroelectric dam, the first time it has done so in years, VTV reported.

Prime Minister Nguyen Xuan Phuc visited northern Ninh Binh province where water levels in the Hoang Long river are their highest since 1985.

Rising sea levels are also threatening Vietnam's more than 3,260 km (2,000 mile) coastline, resulting in increased flooding of low lying coastal regions, erosion and salt water intrusion.

Floods have also affected seven of 77 provinces in Thailand, Vietnam's neighbour to the west, the Department of Disaster Prevention and Mitigation said on Thursday. More than 480,000 hectares (1.2 million acres) of agricultural land have been affected, the department said.

Thailand is the world's second-biggest exporter of rice.

"It is still too soon to tell whether there will be damage to rice crops because most of the rice has already been harvested," Charoen Laothamatas, president of the Thai Rice Exporters Association, told Reuters.

In 2011, Thailand was hit by its worst flooding in half a century. The floods killed hundreds and crippled industry, including the country's key automotive sector.