Secretary-General Ban Ki-moon said the U.N.'s mission chief, Hedi Annabi, and his chief deputy, Luis Carlos da Costa, are among roughly 100 people still buried in the rubble of the five-story headquarters building.
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The U.N. chief said early Thursday that rescuers at the collapsed headquarters building heard "scratching sounds" and located Tarmo Joveer, an Estonian close protection officer, under about 13 feet of rubble. He was given water through a rubber pipe, pulled out and taken to the U.N. mission hospital run by Argentine staff.
"It was a small miracle during a night which brought few other miracles," Ban said.
Speaking by videoconference from Port-au-Prince, David Wimhurst, a spokesman for the U.N. peacekeeping mission, said Joveer was covered in dust and dehydrated, but "he walked out of there unscathed. ... He was very, very grateful to be alive."
Wimhurst said early Thursday afternoon that the dead include 19 U.N. peacekeepers, four international police officers and 13 civilians. The injured include 26 military, nine police and 38 civilians, of whom 24 are Haitian nationals.
Wimhurst said about 160 national and international civilian staffers, 18 police, and 10 military personnel are still missing.
"I think the first 72 hours will be critically important," Ban said. "Now we are approaching 48 hours... I hope that we will have more and more survivors."
"The priority remains emergency search and resuce. People remain alive under the rubble, and we must save as many lives as we can," he said.
Rescue teams from China, the U.S., France and the Dominican Republic have arrived with dogs and listening equipment and Ban said more teams will be arriving soon.
The U.N. chief said he requested helicopters, engineers, medical equipment and medical items from the United States, "as much as they can provide," and requests for transport helicopters and other critical assets will be made to many other countries and international partners.
Ban said Assistant Secretary-General Edmond Mulet will arrive in Port-au-Prince Thursday afternoon to take charge of the U.N. mission and co-ordinate the international relief effort.
"He will immediately begin to work to co-ordinate the assistance and rescue operations, in close co-ordination with the Haitian leadership, including President (Rene) Preval," Ban said.
The U.N.'s Haitian mission - spread across the country - includes 7,000 peacekeeping troops, 2,090 international police, 490 international civilian staffers, 1,235 local civilian staffers and 215 U.N. volunteers, he said. The force, known as MINUSTAH, was brought in after a bloody 2004 rebellion following decades of violence and poverty in the nation.
The secretary-general said the 3,000 peacekeepers in and around Port-au-Prince "are patrolling and they are trying to maintain law and order around the city."
"So far, I think we have been able to maintain such order," Ban said. "We are extremely careful and we will pay attention to prevent any crimes, any violence."
With the U.S. sending 3,500 troops and massive aid to Haiti, the secretary-general was asked whether the U.S. will answer to the U.N. or whether it will operate independently.
Ban said he told the U.N. General Assembly on Wednesday "that all international aid and assistance should be co-ordinated with MINUSTAH, the United Nations" with Mulet in charge of co-ordinating the effort.
Did that mean that Mulet, who was Annabi's predecessor as the top U.N. envoy in Haiti, would direct the U.S. military?
"The force commander of the U.N. peacekeeping operations will co-ordinate, I hope, with the U.S. military assistance team," Ban said. "I am sure that the military leaders will fully co-ordinate with each other."
Ban said U.N. humanitarian chief John Holmes will launch an emergency appeal for Haiti at U.N. headquarters on Friday afternoon, hopefully alongside former U.S. president Bill Clinton, his special envoy for Haiti who had been trying to raise money to rebuild the impoverished Caribbean nation after several devastating hurricanes in 2008.