More than 2,000 US marines were expected to arrive in the region on Monday to bolster US troops and UN peacekeepers already on the ground.
In Brussels, European Union nations pledged more than 420m euros ($604m; £320m) from the EU budget to assist Haiti, with about half the sum dedicated to emergency and short-term aid.
At least 200m euros will be dedicated to funding medium- to long-term rebuilding efforts.
"We recognise that more aid and support is needed, and more has been agreed," EU foreign affairs chief Catherine Ashton told reporters, adding that the EU was working closely with the United Nations, the US and others.
European ministers were also discussing deploying a security mission to help maintain law and order.
On Monday, UN Secretary General Ban Ki-moon said he would recommend that the UN Security Council boost police and troop numbers in Haiti by 3,500.
It came a day after he appealed to frustrated Haitians to be patient over efforts to bring them relief.
Gen Keen, running the US military relief effort, when asked about death toll estimates of between 150,000 and 200,000 people, said: "I think the international community is looking at those figures, and I think that's a start point.
"Clearly, this is a disaster of epic proportions, and we've got a lot of work ahead of us."
Hope for more rescues
Amid the chaos and destruction, a number of people were rescued from collapsed buildings at the weekend.
Among the lucky ones was a seven-year-old girl pulled alive from the ruins of a supermarket.
Nick Davis, BBC News, Port-au-Prince
I'm standing on what would have been the roof of the city bank building. There's steel everywhere, the steel that was supposed to keep it upright. Right now the front of it's just completely collapsed. The rear of the building is still intact. The job now is to see whether or not there are any more bodies still inside.
You've got to bear in mind that this earthquake struck at a time when this place would have been full of people, full of staff members, full of cleaning crews, full of security and customers too.
Forensic teams who have flown in are using mitochondrial DNA samples to hopefully identify the bodies which they've found. But until this steel is cut, until the earth-moving equipment which is just to the other side of me can remove the tonnes of concrete I'm standing on, not much can be done.
At the UN headquarters destroyed in the earthquake, rescuers lifted a Danish staff member alive from the ruins, just 15 minutes after the secretary general visited the site.
And US teams with search dogs also rescued a 16-year-old Dominican girl trapped for five days in a small, three-storey hotel.
The US Agency for International Development (USAID) said on Monday that American teams had pulled 10 people alive from the rubble the day before.
"According to rescue officials, this is the largest number of rescues in a single day in decades of earthquake search and rescue efforts," it said in a statement.
While hopes dim with every passing day, a South African rescue official, Colin Diner, told the BBC he hoped there would be more people found alive.
"What we are seeing is that the buildings have a whole lot of openings, collapsed voids and things, and that always gives you a better opportunity," he said.
UN humanitarian chief John Holmes told reporters on Monday that there were now 43 search and rescue teams on the ground, with 1,700 people involved in the effort.
"More than 70 people have been pulled from the wreckage in the last few days," he said, saying that efforts to find those trapped in the rubble would carry on until there was no longer hope of finding anyone alive.
He played down worries over security, saying that despite incidents of violence, the overall situation was one of calm.
Homeless throng streets
Correspondents say there is a sense of movement at last with the relief effort, although the amount of supplies getting through is still small.
AID PLEDGES TO HAITI
EU - $604m (420m euros; £371m)
US - $100m pledged in immediate aid, with promise of more later
UK - $32m
Norway - $17.6m
France - $14.4m
World Bank - $100m
The BBC's Mark Doyle says that in a slum community in the hills above Port-au-Prince, people have yet to see any government officials or aid workers.
They have camped out on waste ground and are fending for themselves, he says, pulling together to survive.
Meanwhile, our correspondent says, perhaps 5,000 people are lined up in the baking sun outside the US embassy, desperate to get visas to join relatives among the large Haitian-American community in the US.
Several agencies have complained about not being able to get aid through the airport in Port-au-Prince, which is heavily congested and has been taken over by the US military.
Medecins Sans Frontieres urged commanders to speed up the landing of planes carrying medical supplies, after one carrying an inflatable field hospital was turned away on Saturday night.
But Mr Holmes said that initial issues were now being resolved with the introduction through the World Food programme of a slot system to prioritise humanitarian flights.
The head of the US operation at the airport, Col Buck Elton, said on Sunday there had been 600 take-offs and landings since the US took control on Wednesday, and 50 flights had been diverted.
About 60% of the flights coming in were civilian and 40% military, he said.
US troops also said they had set up their first foothold outside the airport to deliver aid carried in by helicopters.
Port-au-Prince's port is badly damaged, and many roads are still blocked by corpses and debris, hampering the delivery of fuel and other supplies.
The Haitian and Dominican Republic governments are planning an alternative 130km (80 mile) humanitarian road corridor to deliver relief from the southern Dominican town of Barahona, the UN said.
Mr Holmes said the UN expected to resolve problems with bringing in fuel from the Dominican Republic in the next day or two.
The UN has launched an appeal for $562m (£346m) intended to help three million people for six months, most of whom are thought to need emergency relief.
The British government has said it will treble its aid to Haiti to £20m ($32m).
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.