The United Nations and relief organisations distributing aid are facing logistic problems [AFP]

Relief workers are still struggling to help thousands of people affected by an earthquake in Haiti, amid difficulties in distributing relief supplies to those who need it most.

International relief organisations and teams from the United Nations are finding it difficult to distribute tonnes of supplies from the airport near Port-au-Prince, the Haitian capital that was devastated by Tuesday's quake.

Haiti's government says that at least 50,000 people have died as a result of the magnitude 7.0 quake. Some relief organisations though say the death toll could be as high as 200,000.

Sebastian Walker, Al Jazeera's correspondent in Port-au-Prince, said that while 200 tonnes of aid was stacked up at the airport, getting relief supplies to those in desperate need has been extremely problematic.

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"This comes down to the complex issue of who is in charge here. The US military has a great deal of control over the number of flights that are landing here," he said.

"We heard that a UN flight carrying aid equipment had to be diverted because the US was landing its own aircraft there. The question of just who makes the decision over how to distribute the aid seems to be what is holding up the supplies.

"At this point, there are thousands camped out in the streets...These people have been sitting out here for days now, and they say that they have not received the food and aid that is ready to be delivered."

People leaving capital  

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.

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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.

Thousands of people are now leaving Port-au-Prince in order to find help. The United Nations has said that many are heading in an easterly direction in hope of eventually crossing into the Dominican Republic.

Quake survivors are also heading north, where destruction from the quake is not as severe, according to satellite images.

However, international aid is still some way from reaching these areas and the arrival of thousands of refugees is likely to make the situation worse.

People are also making their way south to the city of Jacmel, which lies about 80km from the capital.

The UN has 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.

Waiting for aid

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, on Saturday urged patience with the relief operation, saying there would be "many difficult days ahead".

There have been reports of looting by Haitians desperate for food and water [AFP]

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.

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.

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 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.

Source: Al Jazeera and agencies