|About 40,000 bodies have already been buried in mass graves [AFP]
Up to 200,000 people are feared dead as a result of the 7.0 magnitude earthquake that has destroyed much of the Haitian capital Port-au-Prince, officials in the Caribbean country say.
Lorries have been trying to collect the bodies that have been visible on the streets across Port-au-Prince for burial in mass graves outside the city.
"We have already collected around 50,000 dead bodies," Paul Antoine Bien-Aime, Haiti's interior minister, told the Reuters news agency.
"We anticipate there will be between 100,00 and 200,000 dead in total, although we will never know the exact number."
If the casualty figures are accurate, Tuesday's quake would be one of the 10 deadliest on record.
About 40,000 bodies have already been buried, while the bodies of another 2,000 victims have been incinerated at one of Port-au-Prince's rubbish dumps.
Thousands more people are believed to be under the rubble of the buildings that were toppled in the quake.
Alex Larsen, the country's health minister, said that the devastation was such that three-quarters of Port-au-Prince would have to be rebuilt.
Hillary Clinton, the US secretary of state, arrived in Haiti on Saturday to meet Rene Preval, the country's president, and other local officials.
Preval is working out of a police station near the airport after the presidential palace was destroyed, along with several government ministries.
"The government has lost its capacity to function properly, but it has not collapsed," he said.
Ban Ki-moon, the UN secretary general, on Saturday confirmed that Hedi Annabi, the UN special envoy to Haiti, and his Brazilian deputy had died in the quake, which flattened the UN mission's main headquarters in Port-au-Prince.
"I am deeply saddened to confirm the tragic death of my special representative to Haiti, Hedi Annabi," Ban said in a statement.
"His deputy Luiz Carlos da Costa and the acting Police Commissioner, Doug Coates of the Royal Canadian Mounted Police, are also confirmed to have perished."
Waiting for aid
The estimated 300,000 people made homeless by the quake spent a fifth night sleeping on the streets on Saturday, along with many others who fear returning to their homes in case of further building collapses.
Aircraft and ships have arrived with rescue teams, search dogs, tents, water purification units, food, doctors and telecoms teams, but personnel face problems unloading the supplies and getting them into the city.
The UN said that up to 90 per cent of the buildings in Leogane, a town to the west of Port-au-Prince, had been damaged.
"According to the local police, between 5,000 to 10,000 people have been killed [in Leogane] and most bodies are still in the collapsed buildings," Elisabeth Byrs, a spokeswoman for the UN Office for the Co-ordination of Humanitarian Affairs, said.
Between 40 and 50 per cent of the towns of Carrefour and Gressier were also destroyed, the UN assessment team said.
"Search and rescue teams are in these areas," Byrs said, stressing that there was an "urgent need for medical care".
Barack Obama, the US president, said the earthquake had inflicted "heart-breaking" losses and pledged that Washington would do what it takes to save lives and get the country back on its feet.
"The scale of the devastation is extraordinary ... and the losses are heartbreaking," he said.
Obama also urged patience with the relief operation, saying there would be "many difficult days ahead".
Flanked by his predecessors George Bush and Bill Clinton, Obama also announced a national drive to raise money to help survivors.
"President Bush and Clinton will help the American people to do their part, because responding to disaster is the work of all of us", Obama said, speaking in the White House Rose Garden on Saturday.
Bush told journalists that the best way to help Haiti was "just send your cash", and announced a website to help fund-raising - the Clinton-Bush Haiti Fund.
In an attempt to address some of the problems facing aid delivery, the US was given on Friday "senior airfield authority" of Haiti's main airport under an agreement between the Haitian government and the US state department.
Lieutenant-General Philip Breedlove, the US air force deputy chief of staff for operations, plans and requirements, said that the agreement would be in effect until Monday.
The agreement means the US will "schedule and control" flights in and out of the airport, deciding what planes can land and in what order.
Aid flights have been arriving at the airport faster than ground crews can unload them, prompting aviation authorities to restrict non-military flights for fear that jets would run out of fuel while waiting to land.
The USS Carl Vinson, with 19 helicopters onboard, also arrived off Haiti on Friday, opening a second significant channel to deliver help. The helicopters immediately began ferrying water and other supplies into Haiti.
The first supply ship also reached Port-au-Prince's severely damaged port, bringing a cargo of bananas and coal from the town of Jeremie, about 200km away.
|There have been sporadic reports of looting by Haitians desperate for food and water [AFP]
The US plans to send 10,000 US troops to Haiti to help distribute aid and prevent potential rioting among survivors, Mike Mullen, the chairman of the US joint chiefs of staff, said.
In a joint news conference at the Pentagon with Mullen, Robert Gates, the US defence secretary, said the primary goal is to distribute aid as quickly as possible "so that people don't, in their desperation, turn to violence".
Governments across the world have poured relief supplies and medical teams into Haiti.
But huge logistical hurdles and the sheer scale of the destruction have meant people are increasingly frustrated at the lack of help.
"There have been some incidents where people were looting or fighting for food," Alain Le Roy, UN undersecretary general for peacekeeping, told the PBS NewsHour.
"They are desperate, they have been three days without food or any assistance.
"We have to make sure that the situation doesn't unravel but for that we need very much to ensure that the assistance is coming as quickly as possible so that the people who are dying for food and medicine get them as soon as possible."