Five days after a 7.0 magnitude quake killed up to 200 000 people, international rescue teams clawed away at the rubble of collapsed buildings in the wrecked capital, Port-au-Prince, in a race against time to find more survivors.

But logistical logjams kept major relief from reaching the hundreds of thousands of hungry Haitians waiting for help, many of them sheltering in makeshift camps on streets strewn with debris and decomposing bodies.

"I'm going there with a very heavy heart. This is one of the worst humanitarian crises in decades. The damage, destruction, loss of life is just overwhelming," UN Secretary General Ban Ki-moon said as he boarded a flight for Haiti on Sunday.

The United Nations was feeding 40 000 people a day and hoped to increase that to one million within two weeks, he said. "The challenge at this time is how to coordinate all of this outpouring of assistance."

As people turned more desperate and in the widespread absence of authority, looters swarmed over collapsed stores carrying out food and anything else they could find. Fighting broke out between groups carrying knives, ice-picks, hammers and rocks.

President René Préval said 3 500 US troops will help overstretched UN peacekeepers and Haitian police guarantee security in the capital.

"We have 2 000 police in Port-au-Prince who are severely affected. And 3 000 bandits escaped from prison [during the quake]. This gives you an idea of how bad the situation is," Preval told reporters.

Thieves lynched
Residents awoke to find the bodies of thieves lynched by mobs or shot by men claiming to be plainclothes police. A Reuters journalist said he saw the burned body of a man locals said was set ablaze by angry residents who caught him stealing, and two young men lying on the ground with bullet wounds to the head and arms tied behind their backs.

"Haitians are partly taking things into their own hands. There are no jails, the criminals are running free, there are no authorities controlling this," said teacher Eddy Toussaint, part of a crowd staring at the bodies.

Many Haitians streamed out of the city on foot with suitcases on their heads or jammed in cars to find food and shelter in the countryside.

Others crowded the airport hoping to get on planes that arrived laden with emergency supplies and left packed with Haitians. The shell-shocked government has given the US military control over the tiny airport to guide aid flights from around the world.

Dozens of nations have sent planes with rescue teams, doctors, field hospitals, food, medicine and other supplies, but faced a bottleneck at the airport, where fuel was in short supply. Some groups complained that their flights had been diverted to the neighbouring Dominican Republic, forcing them to carry emergency supplies into Haiti overland.

The US military said it had set up a joint task force to coordinate the flow of aid into Haiti under the codename "Operation Unified Response". About 5 000 US military personnel were already involved and an additional 7 500 were scheduled to arrive by Monday.

A fleet of 30 helicopters was flying relief directly to Haitians, while US planes were bringing in supplies and several ships were either off Haiti or on their way.

Scrums for food
On the streets of Port-au-Prince, scarce police patrols fired occasional shots and tear gas to disperse looters and the distribution of aid appeared random, chaotic and minimal.

Hundreds of trucks carrying aid and guarded by armed UN patrols streamed away from the airport and UN headquarters to different parts of the city. But they were soon obstructed on streets clogged with people, vans carrying coffins and bodies and even makeshift roadblocks put up by homeless survivors forced to live and sleep out in the open.

There were jostling scrums for food and water as US military helicopters swooped down to throw out boxes of water bottles and rations. A reporter also saw foreign aid workers tossing packets of food to desperate Haitians.

"The distribution is totally disorganised. They are not identifying the people who need the water. The sick and the old have no chance," said Estime Pierre Deny, standing at the back of a crowd looking for water with his empty plastic container.

Haiti is the Western Hemisphere's poorest country and has for decades struggled with devastating storms, floods and political unrest. About 9 000 UN peacekeepers have provided security since a 2004 uprising ousted one president, but the mission lost at least 40 members when its headquarters collapsed, including its top leaders.

More rescued alive
Aftershocks still shook the capital, terrifying survivors and sending rubble and dust tumbling from buildings.

Three people were pulled out alive from a supermarket early on Sunday. US and Turkish teams freed a seven-year-old Haitian girl, a Haitian man and an American woman from the rubble of the five-storey building. They were dazed but did not appear to be seriously injured.

Trucks piled with corpses have been ferrying bodies to hurriedly excavated mass graves outside the city, but tens of thousands of bodies are still believed buried under the rubble.

Haitian government officials said the death toll was likely to be between 100 000 and 200 000.

Dozens of bloated bodies have been dumped in the yard outside the main hospital, decomposing in the sun. The hospital gardens were a mass of beds with injured people, with makeshift drips hanging from trees.

Haiti's government is struggling to operate as the quake destroyed the presidential palace and knocked out communications and power. Préval is living at the judicial police headquarters and holding Cabinet meetings with foreign ambassadors outside, seated on plastic chairs.

"Everything in Haiti is broken. All the ministries are fallen. There is not one person in the country without a friend or family member dead," said Information Minister Marie Laurence Jocelyn Lassegue. "When they say the government is not fast, we are truly doing our best."

Worshipers gathered on Sunday at churches across the city.

Though many are living on the street, the men somehow turned up in pressed white shirts and ties with dark jackets, and the women in smart linen dresses and head scarfs at the Assembly of God church in the Petionville suburb.

"It has been a week for thanking God for protecting us. We are suffering a lot but praying helps us. We lost our home but our family is safe thanks to God, said Anne Pierre, a 64-year-old whose seven children and 12 grandchildren all survived. - Reuters