At least 18 people have died and more than a dozen are missing in Vietnam after floods submerged homes in central regions and rough seas capsized fishing boats.

Images on state media showed entire villages submerged in Quang Tri and Quang Nam, while murky floodwaters swept through the Imperial City of Hue and the tourist hotspot Hoi An over the weekend.

It comes as another storm threatened fresh downpours.

More than a hundred thousand homes have been submerged during the floods and nearly 46,000 people evacuated, Vietnam's disaster management authority said.

The military staged a dramatic helicopter rescue of eight fishermen who had been swept away by rough seas off Quang Tri province.

Vietnam is frequently lashed by harsh weather in the rainy season between June and November, with central coastal areas most vulnerable.

The country is bracing for a storm rolling in from the South China Sea, with heavy rain again expected.