As many as 1,000 people are feared dead in a remote Haitian town left submerged by disastrous floods.
Authorities fear many bodies remain submerged around Mapou
About 300 bodies have been found so far in the south-eastern town of Mapou, which was described as "a lake".
Rescue workers are moving to try to help thousands of survivors who may have lost relatives, their homes and access to clean water and food.
Disinfectant is to be sprayed in the nearby Dominican Republic town of Jimani to stop the spread of disease.
More than 900 people have been confirmed dead from the floods across Haiti and the Dominican Republic which make up the Caribbean island of Hispaniola.
Two teams of United Nations disaster relief experts will set off for the island on Friday.
Aid workers are scrambling to get chlorine tablets and first-aid kits to Mapou and other stricken towns, helped by US-led peacekeeping forces.
The multinational forces were sent to Haiti to help keep order after the February overthrow of President Jean-Bertrand Aristide.
Three helicopters carrying water, chlorine purification tablets and other supplies have been sent to Mapou and Fond Verettes, where 165 people are said to have died.
Another 100 bodies have been found in the coastal town of Grand Gosier.
"Mapou is in the middle of a valley and the village is practically under water," spokesman Lieutenant Colonel David Lapan told Reuters news agency.
"It is like a lake when you look at it from the air."
Continuing rain has hampered the access even of helicopters to the area, where there is a desperate race to recover the bodies of those who died.
"There are still corpses floating in the water," Marko Kokic of the International Committee of the Red Cross (ICRC) told the BBC World Service.
"It poses a grave health risk for the population there."
He told the World Today programme that aid workers were trying to get hold of small boats so that volunteers could help recover the bodies.
Heavy deforestation by people using trees for fuel greatly aggravated the impact of the rains.
Many flood-hit towns are impossible to reach except from the air.
Even before the flooding, Mapou was said to take three or four hours to reach from Jacmel, the nearest city.
Rivers of mud
Across the border in the Dominican town of Jimani, rescuers continued to dig through rivers of mud, reported AFP.
The town - now a muddy scar in the landscape, after the flood waters drove through - was the worst-hit in the Dominican Republic.
The grim task of collecting and burying the dead continues in Jimani
At least 329 bodies have been found there, and at least 300 people are missing.
Dominican President Hipolito Mejia and the US ambassador, Hans Hatler, have toured the stricken town.
Mr Hatler announced $50,000 in aid, saying more would be delivered as soon as possible.
Nearly 700 ICRC volunteers were reportedly in the town, helping those injured and putting up mosquito nets to protect against outbreaks of malaria and dengue fever.
Officials told Reuters they planned to spray the town with disinfectant to try to halt the spread of disease.