Pedestrians wearing rain ponchos waded through knee-high -- and for some, waist-high -- floodwaters in the city of Hue, with others piloting small motorboats down the flooded streets.

Three measuring stations in Hue recorded rainfall from one metre to 1.7 metres (five feet seven inches) in a 24-hour period from Sunday to Monday, the environment ministry said in a statement.

The previous 24-hour rain record was 0.99 metres, set in Hue in 1999, it said.

Heavy rain has inundated Vietnam's central coastal region since the weekend, closing schools and flooding the former imperial city of Hue, a UNESCO world heritage site.

More than 8,600 people in four central provinces were evacuated to schools and other public buildings since Saturday due to risks from severe flooding and landslides, according to the environment ministry.

"This was the biggest flood I have experienced, with water levels in my house about 40 centimetres higher than that of 1999," said 56-year-old Hue resident Tran Anh Tuan.

"My ground floor is under about two metres of floodwaters. We had moved all essential furniture upstairs. We have been in the dark over a day as power was cut off," Tuan told AFP from his three-storey house in central Hue.

Hue authorities warned residents that rain and flooding may last until Friday.

An image published by state media on Monday showed a room in a main hospital in the city flooded with murky water and two patients seated on gurneys.

- Boats in street -

Tourists in ancient Hoi An town were pictured in state media navigating narrow streets in boats while AFP journalists saw authorities evacuate several people from heavily flooded areas.

Early Tuesday morning, heavy rain triggered a massive landslide of red mud about three kilometres long in coastal Quang Ngai province, leaving about 1,700 people isolated and damaging crops, local authorities said.

"The level of natural disaster risk due to flash floods and landslides is at the highest level," said Mai Van Khiem, director of the National Center for Hydro-Meteorological Forecasting, according to a government website.

Some schools were closed in the cities of Hue and Danang beginning Saturday while the railway linking the country's north and south saw delays due to flooding.

Scientists say human-driven climate change is making extreme weather events like storms and floods more deadly and destructive.

Vietnam's mountainous north and capital Hanoi were under severe flooding in early October following typhoons Bualoi and Matmo.

Natural disasters, mostly storms, floods and landslides, left 187 people dead or missing in the Southeast Asian nation in the first nine months of this year.

More than 240,000 hectares (590,000 acres) of crops were destroyed and 38,000 houses collapsed or were damaged, the General Statistics Office said.

Total economic losses were estimated at more than $610 million, it said.