Vietnamese rescuers raced to find more than a dozen people still missing on Saturday after a week of heavy flooding, with authorities saying at least 55 people have died.

Relentless rain has lashed south-central Vietnam since late October and popular holiday destinations have been hit by several rounds of flooding. Rainfall exceeded 190 centimetres in some parts of central Vietnam over the past week.

Whole city blocks were inundated this week in coastal Nha Trang, while deadly landslides struck highland passes around the Da Lat tourist hub.

At least 55 people have been killed across six provinces since Sunday, while the search continues for 13 others, the environment ministry said in a statement released on Saturday.

Mountainous Dak Lak province was the hardest hit, with more than two dozen fatalities, it said.

Rescuers were still plucking people from treetops and the roofs of homes as floodwaters receded there on Friday, state media reported.

Multiple highways remained impassable on Saturday and 300,000 people were without power, after a blackout that initially affected more than a million, the environment ministry added.

Natural disasters have left 279 people dead or missing in Vietnam and caused more than US$2 billion in damage between January and October, according to the national statistics office.

The Southeast Asian nation is prone to heavy rain between June and September, but scientists have identified a pattern of human-driven climate change making extreme weather more frequent and destructive. (AFP/Reuters)