"The people need urgent help, the flooding won't be over for 10 or 15 more days," Prime Minister Nguyen Tan Dung said on Sunday while visiting one of the disaster-struck areas.

Helicopters have dropped dry food supplies such as instant noodles to stranded villagers. Boats also delivered food and other emergency supplies provided by the Red Cross.

Water levels receded in sunny weather, but that did not ease the predicament of thousands of villagers whose houses were completely submerged and they took refuge on rooftops and dykes.

"This may be the worst flooding since 1945," said Phan Dang Khoa, a Communist Party official in Thach Thanh district of Thanh Hoa where a dyke broke on the Buoi river, causing extensive flooding.

The underdeveloped Southeast Asian country of 85 million faces up to 10 storms a year that cause millions of dollars in damage and kill hundreds of people.

Lekima was the fifth of 2007, but flooding and landslides in the aftermath have been even more devastating. The storm and floods destroyed about 100,000 homes mainly in central provinces and 15,000 hectares (37,070 acres) of rice crops.

The International Federation of Red Cross and Red Crescent Societies in Hanoi said some people who were evacuated last week before the typhoon and returned home, had again been evacuated.

"The situation is worse than first estimated," said Irja Sandberg, country representative for the IFRC.

In Nghe An, large swathes of land were also inundated.

"We have not seen flooding like this in 20 years," Nghe An provincial official Nguyen Xuan Hanh said by mobile phone. "It was so fast and so out of the blue."