Aftershocks rattled the city of two million people as women covered in dust tried to clawed out of the debris of collapsed homes, schools and workplaces, while thousands of stunned survivors walked in a daze through the dust-covered streets.

People pulled bodies from the rubble, covering them with sheets by the side of the road, as others tore at the crumbled masonry to try to find survivors buried beneath collapsed walls.

"The hospitals cannot handle all these victims," said Dr Louis-Gerard Gilles as he helped

"Haiti needs to pray - we all need to pray together," he implored.

The earthquake struck just as children were leaving school on Tuesday afternoon, and US Geological Survey seismologist David Wald reported that its focus was near the Earth's surface, about 10 miles to the west of Haiti's capital.

"Such 'shallow' earthquakes can be the most deadly, and in an area where poor construction makes buildings vulnerable, aftershocks could cause a high number of casualties," Mr Wald warned.

Haiti's ambassador to the US Raymond Joseph described the suffering as "catastrophic," and reported that although the presidential palace had been destroyed, President Rene Preval had survived.

However, French foreign minister Bernard Kouchner revealed that the UN special envoy to Haiti Hedi Annabi, who oversaw thousands of UN troops sent to the country after the enforced exile of former President Jean-Bertrand Aristide in 2004, had been killed.

"It would appear that everyone who was in the UN building, including my friend Hedi Annabi, and everyone with him and around him, are dead," Mr Kouchner said.

The Brazilian military added that at least four of its soldiers were dead, and Jordan said that it had lost three more, while China reported that at least eight of its soldiers had been killed, while 10 more were missing.

Haitian migrant workers and immigrants in the US gathered at community centres and churches throughout the day to share news of their families in Port-au-Prince, and to comfort those who had lost loved ones in the earthquake.

Haitian Times journalist Garry Pierre-Pierre reported from New York City, where Haitian immigrants account for almost half of the one million Haitians living in the US, that "the community feels powerless as yet another calamity hits their country."

"With almost no communication to Haiti in the aftermath of the earthquake, people are desperate for news and the suspense is sending a chill as people try to imagine the extent of this catastrophe."

Mr Pierre-Pierre explained that the earthquake's devastation had been exacerbated by Haiti's poverty.

"Port-au-Prince is home to two million people in an area originally planned for 200,000. Houses are poorly constructed with lax building codes, if any," he said.

More than 80 per cent of Haiti's nine million people are considered to be living in poverty.

The overcrowded shanty towns are occupied by people scratching a living of 70 Haitian gourdes - barely £1 a day - in a country ranked by the UN as having the lowest income per person in the entire western hemisphere.