The death toll in the earthquake that devastated Port-au-Prince could reach 200,000, the Haitian government said Friday.

"We have already collected around 50,000 dead bodies," Interior Minister Paul Antoine Bien-Aime told Reuters. "We anticipate there will be between 100,000 and 200,000 dead in total, although we will never know the exact number."

The UN mission chief in Haiti, Hedi Annabi of Tunisia, and his deputy, Brazilian Luiz Carlos da Costa, are among the dead, UN Secretary General Ban Ki-moon announced Saturday.

Ban and U.S. Secretary of State Hillary Rodham Clinton were heading to see the damage first-hand.

Meanwhile, government workers in Port-au-Prince, Haiti's capital, began burying thousands of bodies in mass graves Friday as tempers continued to rise among survivors waiting for aid.

The Red Cross estimates between 45,000 and 50,000 dead. The agency based its figures on reports from volunteers across the city, said Jean-Luc Martinage, a spokesman for the International Federation of Red Cross and Red Crescent Societies.

Men carry the coffin of an earthquake victim in Port-au-Prince on Friday. (Gregory Bull/Associated Press)

"We consider this as an estimate," Martinage said.

UN officials in Port-au-Prince confirmed that 19 UN peacekeepers, four international police officers and 13 UN staff members are dead. About 100 UN workers are trapped in the rubble of the UN headquarters that collapsed in the quake, while another 50 UN staff are unaccounted for elsewhere.

Ban estimated 50 per cent of the buildings in the capital were damaged or destroyed and said a high proportion of the three million people in the area had no food, water, shelter or electricity.

The desperate situation prompted the Brazilian military to warn aid convoys to add security to guard against looting.

"Unfortunately, they're slowly getting more angry and impatient," David Wimhurst, spokesman for the Brazilian-commanded United Nations peacekeeping mission, told The Associated Press. "I fear, we're all aware that the situation is getting more tense as the poorest people who need so much are waiting for deliveries. I think tempers might be frayed."

Many Haitians have been without food or clean water since Tuesday, the day of the quake, sparking fears of widespread malnutrition and dehydration.

UN humanitarian spokeswoman Elisabeth Byrs said peacekeepers were maintaining security in Haiti, despite the challenges.

"It's tense but they can cope," Byrs said. "People who have not been eating or drinking for almost 50 hours and are already in a very poor situation, if they see a truck with something … or if they see a supermarket which has collapsed, they just rush to get something to eat."

Emilia Casella, the UN World Food Program spokeswoman, said officials in Port-au-Prince have recovered most of the supplies from four warehouses in the city after reports that food stocks had been looted.

Casella said the looting reports were overblown. She said staff would soon be handing out about 5,400 tonnes of food, representing about a third of the food aid the UN had stored in Haiti before the quake hit.

"The food is there," she said. "They are also working on getting a peacekeeper contingent to secure the locations."

'Not a drop left'

The CBC's David Common, reporting from the capital, said he witnessed people swarming a nearby pickup truck carrying bags of clean water.

"All the water was gone in about 30 seconds. Not a drop left. The vehicle was rocking because people had rushed it so quickly."

Canadian medics Master Cpl. Richard Paul, left, and Cpl. Alex Robitaille help an injured woman at a temporary medical clinic in Port-au-Prince on Friday. (Adrian Wyld/Canadian Press)

Canadian medical personnel with the Disaster Assistance Response Team have been inundated with injured people, Common reported.

"We want to help them as much as we can," Dr. Frank Cervenko said.

In addition to DART, another 800 Canadian military personnel may be sent to Haiti to help relief efforts, officials confirmed Friday night.

Belgian aid worker Ronald Ackerman, who runs one of the first international emergency hospitals, compared the medical challenges after the earthquake to "war medicine."

"You have to do primary things — amputation, cleaning wounds, keeping them alive. That's all you can."

Meanwhile, the grim work of dealing with the dead continued. Haitian President René Préval said that over a 20-hour period, government crews removed 7,000 corpses from the streets and morgues and buried them in mass graves.

Thousands of Haitians spent another night outside, and many won't return to their homes, fearing that continuing aftershocks will knock down weakened structures.

Thousands of homes, including the National Palace, were destroyed or damaged in the 7.0 magnitude quake, and at least 300,000 people are estimated to be homeless.

"The hospitals have effectively collapsed," Common said. "I saw people being treated out on the street or simply injured people not being treated at all, doing whatever they could to stay alive essentially until they could do more."

Rescue workers continue to search for survivors, but the chances of finding people alive are becoming remote. Most experts say there's a three-day window to locate people trapped under rubble following a disaster.

While aid pours into the country from governments around the world, the relief effort is hampered by bottlenecks.

Runways at the airport are clear but aid planes are being forced to wait for hours to land. The Haitian government said there was no room on ramps for planes to unload their cargo and some planes on the ground didn't have enough fuel to leave.

CBC News reporter Sasa Petricic arrived with the advance element of Canada's Disaster Assistance Response Team. He said the jet circled the Port-au-Prince airport for about three hours before it could land, because the tarmac was too crowded with aircraft.

The damaged seaport continues to prevent ship deliveries and aid workers have been blocked by debris on inadequate roads and by survivors gathered in the open out of fear of aftershocks. Engineers from the UN mission have begun clearing some main roads.

"We need food," said Sylvain Angerlotte, 22. "The people are suffering. My neighbours and friends are suffering. We don't have money. We don't have nothing to eat. We need pure water."

The International Red Cross has estimated three million people — a third of the population — may need emergency relief that includes shelter, food and clean water.

Governments and government agencies have pledged about $400 million worth of aid, including $100 million from the United States.

About 3,000 police and international peacekeepers have become responsible for security in the capital. About 5,500 U.S. soldiers and Marines are expected to be in Haiti by Monday.

Wimhurst, the mission spokesman, said Haitian police "are not visible at all," no doubt because many had to deal with lost homes and family members. The first U.S. military units to arrive took on a co-ordinating role at the airport.

With files from The Associated Press