The death toll from flooding in north-western Haiti in the wake of tropical storm Jeanne has risen to more than 1,000, local and UN officials say.
Gonaives residents are in dire need of food and clean water
Relief workers fear that many more bodies will be found, as waters recede near the stricken city of Gonaives.
Rescuers are struggling to aid victims, and burying the dead in mass graves to try to prevent the spread of disease.
United Nations Secretary General Kofi Annan has appealed for urgent international aid for Haiti.
The BBC's Jeremy Cooke, who visited Gonaives on Wednesday, says the main street is like a river, flowing with filthy, brown water.
Survivors wade through the mud - sometimes waist-deep - trying to salvage furniture or find food.
Every truck moving, full or empty, is mobbed by survivors desperate for aid , our correspondent says.
Many residents have been forced to take shelter on rooftops, as bloated bodies float along the streets.
"There is a risk of epidemic... There is no electricity, the morgues are not working," Prime Minister Gerard Latortue said.
Later on Wednesday trucks dumped dozens of unidentified bodies into a mass grave in Gonaives.
The confirmed death toll has reached 1,013 in Gonaives, with about 1,200 more missing.
The UN World Food Programme (WFP) estimates 175,000 people are without food, water and electricity.
UN helicopters have already taken emergency supplies to Gonaives.
The WFP said one of its food convoys had also arrived in the city and another would follow.
However trucks are struggling to get through because of floodwaters.
"We can only drink the water people died in," a Gonaives farmer told the Associated Press news agency.
In his international appeal for support, Mr Annan said he was "deeply saddened by the heavy loss of life and destruction".
UN peacekeeping troops - sent to restore order after President Jean-Bertrand Aristide was overthrown in February - are working with aid agencies to help the victims.
Haiti is chronically vulnerable to flooding and mudslides because of widespread deforestation.
"When you remove vegetation, the topsoil washes away," an aid worker told the Associated Press news agency.
In the neighbouring Dominican Republic - which has retained much of its forest cover - the death toll from Jeanne was 19.
NORTHERN HAITI UNDER WATER
Gonaives, the worst-affected city, is still largely under water. More than 1,000 are reported dead there, and as many missing. Carcasses litter the streets, sewers have burst open, and peacekeepers have had to fire into the air to control crowds desperate for food.
In Port-de-Paix and Northwest province, at least 70 are reported dead. The city is described as under a dense crust of mud.
Bodies swept out to sea have washed up on La Tortue island, though aid agencies say the island itself was not hit as badly as at first thought.