John Gagen, Federation of the Red Cross and Red Crescent, Hanoi

Government officials say they fear the death toll could rise further as links are re-established with affected areas near the cities of Hue and Da Nang, about 600 km (375 miles) southwest of the capital, Hanoi.

Vast swathes of land are submerged and many districts are cut off by land, air and sea. Several provinces have declared states of emergency.

Downpours - which over the last week have dumped 600 mm (two feet) of rain on the flood-prone region - are forecast to continue.

Lack of drinking water is expected to be a growing problem, along with the possible outbreak of epidemics.

"The losses are very heavy," the Minister of Agriculture and Rural Development Le Huy Ngo, told Vietnam television.

He is heading a government emergency mission dispatched to Da Nang.

"According to our initial estimates, hundreds of people have died and hundreds of thousands of homes are submerged," he said.

He said severed transport links were causing rescuers "huge problems".

Trains trapped

The country's ancient capital Hue - now a major tourist attraction home to 1 million people - is virtually isolated, with up to three metres (10 feet) of water around its famed citadel.

The airports at Hue and Da Nang have been closed and rail services have ground to a halt, with six trains trapped on the line linking Hanoi and Ho Chi Minh City in the south.

Tens of thousands of people are homeless

National Highway 1, the country's north-south lifeline, is flooded in a number of places.

The governor of Thua Thien Hue province, Nguyen Van Me, said 48 people had died in his province alone, including three rescuers from the border guard.

He said four rescue helicopters had been unable to reach hundreds of people stranded on their rooftops, who have been without power or telephones for three days.

Water 'still rising'

A woman rows herself to safety in Hoi An

Vietnam TV said the air force had sent four transport planes and seven helicopters to bring food supplies from Hanoi to the region.

The army has also been using amphibious tanks to reach those stranded.

"Water is everywhere and still rising," said Le Van Thu of the flood and storm control committee in Quang Nam province, where 150,000 houses are submerged, along with thousands of hectares of rice.

Central coastal Vietnam is regularly hit by bad weather. Last year, storms and floods killed 397 people in the region, while several people were killed last month by tropical storm Eve.