Disaster Management Minister Mahinda Amaraweera said medical units had been rushed to the central and eastern regions, where hundreds of thousands have been forced to take shelter in cramped, state-run relief camps.

"We are very conscious of the fact that there can be water-borne diseases and we brought medical staff from other areas to help out," Amaraweera told AFP. "There are no reports of diarrhoea, but we are taking precautions."

More than one million people were initially displaced in the flooding triggered by unusually heavy monsoon rains in the past week.

The state Disaster Management Centre said 32 people had been officially confirmed dead, with another 12 missing.

UN agencies in Colombo said that providing relief for those in the worst affected areas was a serious challenge, and that they would shortly issue an international appeal for funding.

"A lot of work needs to be done after the water goes down, but first we have to assist people in welfare centres, to make sure they get adequate food, medicines and clean drinking water," UNICEF spokesman Mervyn Fletcher said.

The UN children's agency was helping to purify millions of litres of drinking water for distribution in the affected regions.

Amaraweera said initial surveys showed that vast tracts of farmland had been destroyed, but added that it would be days before an accurate estimate of the economic impact could be made.

Nearly one fifth of Sri Lanka's rice farms were affected by the floods, along with other vegetable crops, triggering immediate price rises in retail markets across the country.

Government officials said at least 30,000 homes had been damaged or completely destroyed by the floods and mudslides.

In the north-central region of Habarana, the carcass of a drowned baby elephant was found Thursday atop a 15-foot (five-metre) tree that had been submerged by the floodwaters.

Weather conditions improved across the island Saturday, but the weather bureau in Colombo said there was a possibility of further rains.

The improved weather opened up the main roads leading to the key eastern towns, where a consignment of food, bottled water and medicines donated by India was being distributed Saturday.

Some 3,000 soldiers have been deployed to help with the relief efforts, along with trucks and air force helicopters.

A large number of those forced out of their homes had only recently been resettled after decades of ethnic conflict between Tamil Tiger rebels and government forces.

Many had also seen their livelihoods wrecked before by the December 2004 Asian tsunami.

Sri Lanka depends on monsoon rains for irrigation and power generation, but the seasonal downpours frequently cause death and property damage in low-lying areas as well as mountainous regions.

The island's two main monsoon seasons run from May to September and December to February.