|Hundreds of people have been hurt in the quake, which reduced Port-au-Prince to rubble [AFP]
The United Nations and international humanitarian agencies are preparing to begin aid efforts in Haiti, after an earthquake in which many people are feared to have been killed.
Thousands of people living in and around Port-au-Prince, the Haitian capital, are thought to have been trapped in the rubble of buildings that collapsed during the earthquake on Tuesday evening.
Elisabeth Byrs, a spokeswoman for the UN's Office for the Co-ordination of Humanitarian Affairs, said that search and rescue teams were "working against the clock" to save lives.
About 37 search and rescue teams from a global network have been mobilised by the UN.
The International Federation of Red Cross and Red Crescent Societies said on Wednesday that its relief plans are based on a "maximum of three million people".
Jean-Luc Martinage, a Federation spokesman, said that "a massive international aid operation was needed" in the wake of the magnitude 7.0 quake, which was centred about 15km inland, west of the capital.
Aid agencies said that access to trapped people has restricted by debris, while electricity, water and phone services were down.
'City in darkness'
Rene Preval, Haiti's president, told the Miami Herald on Wednesday that the scene in his country was "unimaginable" and that he believed thousands of people had died.
"Parliament has collapsed. The tax office has collapsed. Schools have collapsed. Hospitals have collapsed ... There are a lot of schools that have a lot of dead people in them," he said.
Jean-Max Bellerive, Haiti's prime minister told US news channel CNN that the death toll could be "well over 100,000".
A Food for the Poor charity employee said that there were likely to be many casualties given the destruction he had witnessed in the capital.
"I think hundreds of casualties would be a serious understatement," Rachmani Domersant, the charity's operations manager, said.
Karel Zelenka, a Catholic Relief Services representative in Port-au-Prince, told colleagues in the US that "there must be thousands of people dead", according to a spokeswoman for the aid group.
Sebastian Walker, Al Jazeera's correspondent in Port-au-Prince, said that efforts to get aid to those affected by the quake have been complicated by the scale of the destruction.
"We have seen from the air some of those houses that have been completely destroyed. We have been speaking to some people at the airport, who have been telling us some horrific stories of the damage caused. Individuals have each said that they know of dozens of deaths," he said.
"There is only one plane here [that has brought aid] and humanitarian supplies to the people of Haiti - it arrived from Venezuela. The actual aid aeroplane that we were trying to get a ride on is still in Santo Domingo, the capital of the Dominican Republic, as far as we know."
Ann Rose Schoen, a freelance journalist reporting from Port-au-Prince, said that downtown Port-au-Prince had been particularly badly hit.
"People are sitting in the streets ... there are dead bodies, sometimes covered, soemtimes not covered, laying there also. Children are crying and [people] don't know what to do. I saw people walking around with their suitcases," she told Al Jazeera.
Hospitals, schools and hotels collapsed in the capital, raising fears that the injured would have nowhere to go to get treatment.
"We have reports of some of the most important hospitals in Port-au-Prince have been severely impacted by the earthquake," Paul Conneally, the Head of Media at the International Federation of Red Cross and Red Crescent Societies, told Al Jazeera.
The presidential palace in the capital was among the buildings badly damaged in the earthquake.
Raymond Joseph, Haiti's ambassador to the United States, on Wednesday called for international help in the rescue and relief effort.
"The palace and quite a few government buildings have collapsed ... We were able to always to get though to the First Lady ... she said please ask the US, ask the world to send a hospital ship.
It is a must for us now because some of the hospitals have been affected ... In the meantime I am asking for international solidarity with Haiti."
UN staff 'missing'
Alain Joyandet, the French secretary of state for co-operation, told the AFP news agency that up to 200 people were missing after the Hotel Montana was levelled.
The Caribbean nation of nine million is the poorest country in the Americas with an annual per-capita income of $560. It ranks 146th out of 177 countries on the UNDP Human Development Index
More than half the population lives on less than $1 a day and 78 per cent on less than $2. There is a high infant mortality rate and the prevalence of HIV among those between ages 15 and 49 is 2.2 per cent
Haiti's infrastructure is close to total collapse and severe deforestation has left only two per cent of forest cover
About 9,000 UN police and troops are stationed in the country to maintain order
"We know there were 300 people inside the hotel when it collapsed, only around 100 have got out, which greatly concerns us," he said.
Television footage showed long cracks in many of the buildings that were still standing.
Preval said on Wednesday that Hedi Annabi, the chief of the UN mission in Haiti, had been killed in the earthquake.
The United Nations headquarters in the capital was severely damaged in the quake and the world body said that up to 200 of its staff in Haiti were unaccounted for.
Fourteen UN workers were confirmed dead late on Wednesday by Susana Malcorra, head of the UN department of Field Support.
But Jordan reported that three of its peacekeepers were killed and 21 wounded in the quake. Brazil said that 11 of its peacekeepers were killed while eight Chinese soldiers were buried in rubble and 10 were missing, state media said.
The magnitude 7.0 quake's epicentre was about eight to 10km deep, a relatively shallow depth which was likely to have magnified the destruction, according to seismologists.
The quake, which was followed by at least 27 aftershocks up to 5.9 in magnitude, prompted a tsunami alert for parts of the Caribbean that was later cancelled.
Thoughts and prayers
Barack Obama, the US president, said his thoughts and prayers were with the people of Haiti and that he has directed his administration to provide a swift, co-ordinated aid effort to the country.
He said that the first US search and rescue teams would arrive in Haiti on Wednesday morning local time to help deal with the "cruel and incomprehensible" tragedy.
Hillary Clinton, Obama's secretary of state, said the US would provide civilian and military disaster relief assistance.
Tuesday's quake was felt as far away as southeastern Cuba, about 257km from the epicentre, prompting Cuban authorities to evacuate coastal residents because of the initial tsunami threat.
|Many people are feared buried under the rubble of buildings that fell in the quake [AFP]
Soldiers at the US naval base at Guantanamo Bay in eastern Cuba also felt the quake but there was no damage to the base or the prison where the US holds about 200 foreign detainees.
Chief Petty Officer Bill Mesta, a sailor at the base, said troops had begun checking stockpiles of blankets, tents and other relief supplies in anticipation that they will be asked to help in the relief effort.
The last major earthquake that hit Haiti - a magnitude 6.7 quake – struck in 1984.
Already the poorest nation in the Americas, Haiti has been hit by a series of disasters recently and was battered by hurricanes in 2008.
Michael Zamba of the Pan American Development Foundation said that the disaster would be a "tremendous setback" for Haiti.
"A year ago Haiti was hit by four back-to-back tropical storms and hurricanes. That wiped about 20 per cent off the Gross Domestic Product," he told Al Jazeera from Washington DC.
"It has not yet recovered from that last series of natural disasters and this only compounds the situation.
"Haiti is a food insecure nation, it is a nation that needs a lot of food assistance, this is only going to push it back further."
Source: Al Jazeera and agencies