Haiti earthquake survivors await global aid effort
Desperate earthquake survivors plead for aid
Hundreds of thousands of Haitians are awaiting the start of a global rescue effort in the wake of the country's devastating earthquake.
BBC correspondents say the situation is increasingly desperate, with no coordinated rescue plan so far and aid only trickling in.
The search for survivors continues but rescuers have little lifting equipment and are often using their bare hands.
Tens of thousands are feared dead and up to three million affected.
US Secretary of State Hillary Clinton has said the disaster is "unimaginable" and pledged long-term American assistance.
AT THE SCENE
Matthew Price, BBC News, Haiti
It is clear that many who were brought to L'Hopital de la Paix in Port-au-Prince with injuries have since died here. One man with tears in his eyes pointed to his young daughter lying on the dirty tiled floor.
She has two broken legs and a large gash in her head. Her sister is already dead. "Ca va?" her father asks. "Oui," she replies softly, but she is not okay. In pockets, there is barely anything left of this city and so far the people are largely having to cope on their own.
International Development Secretary Douglas Alexander said: "This is a tragedy on a massive scale. Britain is playing its part in the huge international response."
US President Barack Obama said the "people of Haiti will have the full support of the United States" in an "aggressive" aid campaign.
Mrs Clinton cancelled a trip to Asia to deal with the crisis. She said there were tens of thousands of casualties in Haiti and that tens of thousands of buildings had collapsed. "This is going to be a long-term effort," she said.
Her husband, Bill Clinton, the UN special envoy for Haiti, told the Washington Post the quake was "one of the great humanitarian emergencies in the history of the Americas".
The USS Carl Vinson aircraft carrier will arrive on Thursday. The USS Bataan, carrying a Marine expeditionary unit, is also on its way. The Pentagon said it was "seriously considering" sending thousands of marines.
The World Bank is funding $100m of emergency aid.
Whole areas of the Haitian capital have been flattened
The World Food Programme is working on supplying 15,000 tonnes of food and the Red Cross has begun a $10m appeal.
The help is desperately needed as there is no coordinated rescue at present.
Doctor's assistant Jimitre Coquillon told Associated Press: "This is much worse than a hurricane. There's no water. There's nothing. Thirsty people are going to die."
Haitian President Rene Preval could not give an official estimate of the dead, saying: "I don't know... up to now, I heard 50,000... 30,000."
He spoke of how he stepped over dead bodies and heard cries of those trapped in the parliament building.
Haiti is the poorest country in the western hemisphere and correspondents say it simply does not have the infrastructure to manage a rescue operation.
A rescue team prepares to depart from Mexico City
One Chilean UN peacekeeper told Reuters: "We just don't know what to do. You can see how terrible the damage is. We have not been able to get into all the areas."
The UN peacekeepers, who played a key role in maintaining public order in Haiti even before the quake, have been deployed to control any outbreaks of unrest as reports come in of looting.
The UN says 16 personnel are confirmed dead and more than 100 staff are still unaccounted for. They include UN mission head Hedi Annabi. Brazil says the death toll of its peacekeepers has risen from 11 to 14.
Medical aid agency Medecins sans Frontieres reported a "massive influx" of casualties at its makeshift clinics, many of them with severe injuries.
Patients with "severe traumas, head wounds, crushed limbs" have been streaming into MSF's temporary structures but the agency is only able to offer them basic medical care, spokesman Paul McPhun told reporters.
Thousands of Haitians spent a second night in the open on Wednesday, too scared to sleep inside damaged buildings. Many sang hymns to keep up their spirits.
The BBC's Matthew Price visited the grounds of one hospital and spoke of seeing about 100 bodies - but there were many people bedding down for the night to sleep among the dead.
The 7.0-magnitude quake, Haiti's worst in two centuries, struck at 1653 local time (2153 GMT) on Tuesday, just 15km (10 miles) south-west of Port-au-Prince and close to the surface.
Meanwhile, the Red Cross has set up a web site at www.icrc.org/familylinks on which people in Haiti and overseas can register the names of missing relatives.
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