Helicopters and trucks filled with food and other supplies have pushed further into the devastated provinces. But National Highway One, south of the worst-hit province of Thua Thien Hue, remains closed, stranding truckloads of relief supplies in Danang.

The mountain pass north of Danang was hit by a major landslide last week, and road crews have been working around the clock to blow up massive boulders and build a temporary bridge where the highway was completely washed away. The only railway link between the north and the south of country is still closed.

The Vietnamese authorities say a week of extensive flooding in central provinces has killed nearly 500 people. The Central Committee for Flood and Storm Control estimates that over one million people face food shortages.

State television has shown starving villagers mobbing military helicopters and Red Cross vessels carrying relief supplies.

Better weather is forecast for Monday and water levels have dropped significantly in most areas, although some parts of the province of Quang Binh are still covered in almost a metre of water.

On Sunday, army planes delivered 1.6 tonnes of medication to Hue, home to nearly half the population of Thua Thien Hue province. Another 70 tonnes of food, tents and blankets are stockpiled at Hanoi airport waiting to be delivered on Monday.

Widespread damage

Road access to Hue has been restored from the North

Eight provinces, spanning 600km of Vietnam's poorest region, were hit by the flooding, which commentators say was the most serious this century.

The authorities are also concerned about the spread of disease, and a lack of drinking water. Hue's hospital is full, and facing the prospect of a diarrhoea epidemic.

The floods caused a trail of destruction estimated at $50m since last week. Radio Voice of Vietnam says about one million homes were damaged.

The Red Cross has launched an international appeal for $3m, and street stalls have been set up nationwide to collect donations for victims.