|Many Haitians are living on the streets, fearing aftershocks will topple damaged buildings [AFP]
A powerful aftershock has hit Haiti, eight days after an earthquake devastated the Caribbean country, the US geological survey says.
There were no immediate reports of damage or casualties from Wednesday's temblor, which is said to have occurred at 11:03 GMT [6.03am local time], about 56km northwest of the capital of Port-au-Prince.
The aftershock, first estimated at 6.1 magnitude then revised to 5.9, came against a backdrop of growing frustration among residents over the slow pace of relief supplies.
Al Jazeera's Tony Birtley, reporting from Port-au-Prince on Wednesday, said: "Aid is still not coming through and the hours are passing. And since the aftershock, camps have really been filling up.
"The people here don't trust anything anymore and the future is so unclear. They need food, they need medical supplies and they need it quickly."
On a positive note, despite the scale of the devastation in the city, teams from many different countries were showing that it was worth continuing the search for survivors, he said.
Earlier, Al Jazeera's Zeina Khodr, reporting from the capital, said the aftershock caused terror among the thousands of people struggling in harsh conditions after last Tuesday's quake, which toppled buildings and left the survivors struggling to find food and water.
"The minute the earth shook, everyone started to scream. They were praying and singing religious songs. People are still very traumatised here," she said.
"It was 6.30 in the morning, but people had taken to the streets with whatever belongings they had."
Al Jazeera's Teresa Bo, reporting from Petit Goave, a coastal Haitian town, said: "Everybody left their homes, whatever was left of their homes, very early in the morning.
"They were telling us how afraid they were. What we do know is that many of the buildings that were already damaged by the earthquake, collapsed.
"People were completely terrified."
UN mission plan
The aftershock came just hours after the United Nations said it would send an additional 3,500 additional troops and police to Haiti to assist the growing international relief operation.
Defending the UN against criticism that millions of Haitians still do not have food or water, Ban said "the situation is overwhelming".
The 15-member UN Security Council, "recognising the dire circumstances and urgent need for a response", on Tuesday unanimously backed a request by Ban Ki-moon, the UN chief, to reinforce the 9,000-strong UN force in the Caribbean nation.
But he said that "initial difficulties and bottlenecks" that held up supplies were being overcome and UN relief operations were "gearing up quickly".
"We must do all we can to get these extra forces on the ground as soon as possible so that they can help maintain order and deliver humanitarian assistance," Ban said.
The UN move came as the Haitian government said on Tuesday that the number of people killed in last week's earthquake had risen to 75,000, with another 250,000 injured and one million left homeless.
Just 121 people have been pulled alive from the rubble by rescue teams, the UN said on Wednesday.
There was a rare moment of hope on Tuesday as rescue workers pulled an elderly woman out from under the collapsed home of Haiti's archbishop.
The rescue team said it believed two more people were trapped alive under the same building.
Anna Zizi was placed on a makeshift stretcher, put on a drip, covered with a heat-conserving wrap and taken to a hospital, witnesses said.
"It was an amazing thing to witness, no one could believe she was still alive," Sarah Wilson of British charity Christian Aid said.
"She was singing when she emerged. Everyone clapped and cheered."
'Signs of improvement'
Winnie Romeril, from the American Red Cross, told Al Jazeera that "there are real signs of improvement" for those that survived the quake but had spent a week struggling to get food, water and medical treatment.
"There are little micro-economies springing up, there's food out there, people are buying it," she said.
For her part, Kathie Neal, director of development for SOS Children, the world's largest orphan charity, told Al Jazeera that the organisation will be working closely with the UN, Care and the Red Cross.
"The children will be handed over to us to look after and to help them retrace their families," she said.
"We have two villages in Haiti and those villages will act as base camps and for some of these children that will be coming in, they will need food and medical care."
A week on after the quake, the UN food agency has distributed rations for nearly 200,000 people.
But the UN says three million to 3.5 million people have been affected by the quake and it hopes to increase the number of people receiving food to one million this week and at least two million in the following two weeks.
Badly damaged hospitals have started to function, water supplies have been increasing and more tents and temporary shelters have started to arrive, Ban said.
Al Jazeera and agencies