A total of 16 UN personnel were confirmed dead late Wednesday in the earthquake that decimated Haiti's capital, with 100 to 150 workers still unaccounted for, including the mission chief and his deputy.

Eleven Brazilian peacekeepers and five international police officers — three from Jordan and one each from Chad and Argentina — were killed in the "horrendous" quake, Secretary-General Ban Ki-moon announced late Wednesday.

UN officials said 56 others were injured. Seven who were seriously hurt were evacuated from the country.

"Many continue to be trapped inside UN headquarters and other buildings," Ban said, noting that includes the UN's mission chief, Hedi Annabi, and his chief deputy, Luis Carlos da Costa.

"Other peacekeepers and civilian staff from many member states remain unaccounted for," he said.

"It is our estimate that …hundreds of people were still working inside the building …Therefore it will be in the range of 100 to 150 that I'm quite concerned about."

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UN troops, mostly from Brazil, were trying to rescue people from the wreckage of the five-storey building, UN peacekeeping chief Alain Le Roy told reporters.

Reuters reported that Haitian President René Préval confirmed that Hedi Annabi, the Tunisian diplomat in charge of the UN mission in the country, is dead.

Hedi Annabi is the UN secretary general's special representative and head of the UN stabilization mission in Haiti. France's foreign minister said Annabi was among the dead when the UN headquarters in Haiti collapsed. (Ariana Cubillos/Associated Press)

However, the UN had yet to confirm Annabi's death. French Foreign Minister Bernard Kouchner earlier told two French radio stations that Annabi and most of the workers inside were likely dead.

There was no word on the mission's No. 3 representative, Canadian Kim Bolduc, who was appointed to the post in November.

Some 9,000 peacekeepers, including at least 95 Canadians, have been in Haiti since 2004 as part of an international peacekeeping force.

Foreign Affairs Minister Lawrence Cannon said Canada has 82 police officers, seven correctional officers and five Canadian Forces members as part of the peacekeeping force. Two of the Canadian police officers remain unaccounted for, Cannon said.

The UN confirmed 14 peacekeepers have been killed.

The loss of UN forces is an added blow to aid efforts in Haiti.

The force was brought in after a bloody 2004 rebellion following decades of violence. The entire staff includes 7,000 peacekeeping troops, 2,000 international police, 490 international civilian staffers, 1,200 local civilian staffers and 200 UN volunteers.

UN World Food Program head Josette Sheeran said Wednesday the agency is airlifting an additional 86 tonnes of food, enough for half a million emergency meals, from its emergency hub in El Salvador.

With files from The Associated Press