Floods caused by a tropical depression in Vietnam have killed 43 people, one of the highest death tolls recorded in the country from flooding, officials say.

Key points: The hardest hit province is Hoa Binh in northern Vietnam

The hardest hit province is Hoa Binh in northern Vietnam More than 17,000 households have been evacuated and more than 200 homes have collapsed

More than 17,000 households have been evacuated and more than 200 homes have collapsed More than 200 people were killed in storms in Vietnam last year

Another 34 people were missing and 21 were injured after rains caused landslides and flooding, mostly in northern and central Vietnam, according to the Vietnam Disaster Management Authority.

In the hardest-hit northern province of Hoa Binh, 17 people died and 15 others were missing.

The casualties included four families whose houses were buried in a landslide early on Thursday (local time) while they were sleeping, killing nine and leaving nine others missing, disaster official Quach Viet Hoang said.

"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 north-western Hoa Binh province, told state-run Vietnam Television (VTV).

More than 17,000 households have been evacuated, while 200 homes have collapsed. ( Supplied: Vietnam Television )

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 tropical depression hit central Vietnam on Tuesday and brought heavy rains.

Hoa Binh province declares state of emergency

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 also damaged and about 40,000 animals were killed or washed away.

Hoa Binh province in the north-west declared a state of emergency and opened eight gates to discharge water at Hoa Binh dam, Vietnam's largest hydroelectric dam, for the first time 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-kilometre 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.

More than 1.2 million acres of agricultural land have been affected, the department said.

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

Rains caused landslides and flooding mostly in northern and central Vietnam. ( AP: Vietnam News Agency )

Reuters/AP