The international community's outpouring of support to assist victims of this week's devastating earthquake in Haiti is encouraging, UN Secretary- General Ban Ki-moon said Thursday, as rescue efforts are ramping up in the Caribbean nation with the arrival of teams and supplies from around the world.

Although it will be days before an overall casualty figure can be ascertained for the 7.0 magnitude tremor which devastated the capital, Port-au-Prince, "I feel it will be very high," Ban told reporters at the UN Headquarters in New York. "Clearly, this is a major humanitarian disaster."

The large scale of the international response to the disaster is "most heartening," he said, with people around the world expressing their support for Haiti, the Western Hemisphere's poorest country.

On Wednesday night, members of the UN General Assembly pledged their assistance to the earthquake victims, and the secretary- general said he has received numerous calls and letters from people expressing their solidarity with the Haitian people and also with offers of material support.

"Haiti needs every ounce of help we can offer," he underscored Thursday, with the top priority remaining search-and-rescue operations to save those who are trapped under rubble.

Rescue teams from countries including China and France have reached the capital, and the first 72 hours of the operation to save victims will be critical, Ban said.

Needs -- including medical supplies, food, water, tents and heavy equipment -- are both "huge" and "immediate," he said.

The secretary-general said that he has asked the United States Government to provide as many helicopters, engineers and medical supplies as possible.

He has dispatched Edmond Mulet, his former special representative to Haiti and current assistant-secretary-general for peacekeeping operations, to Haiti to assume full command of the UN Stabilization Mission in Haiti (MINUSTAH).

The tremors have also taken a toll on the UN, with nearly 200 personnel serving with MINUSTAH -- including Hdi Annabi, the secretary-general's special representative -- still unaccounted for.

It was announced Thursday that four police, 19 soldiers and 13 civilian staff members with the UN mission have died.

The Christopher Hotel, which houses the UN headquarters in Haiti, and other buildings hosting the world body's offices collapsed in the tremors.

Some eight UN workers have been pulled alive from the rubble, including Tarmo Joveer, 38, an Estonian close protection officer who was rescued from the Christopher Hotel this morning.

Some 3,000 of MINUSTAH's troops and police are in and around Port-au-Prince, and are helping to maintain order and assist in relief efforts. They have also started to clear some of the capital's main roads to allow aid and rescuers to reach those in need.