But billions of dollars will be needed to repair the damage created by the earthquake and tidal wave that hit countries from southeast Asia to the Horn of Africa, said Undersecretary-General for Humanitarian Affairs Jan Egeland, who is also the U.N. emergency relief coordinator.
"A very, very major - perhaps one of the most devastating natural disasters ever - is confirmed," he told reporters Tuesday.
"Millions and millions of people are affected. They have had their water supplies destroyed, they have lost their livelihoods, homes, and many of them have lost relatives."
So far, he said,have reached tens of millions of dollars.
"The international assistance has been immediate and generous," Egeland said. "The U.S. at US$15 million (euro11 million) is one of the most generous pledges so far. It is exactly what we need to get started ... but we will need very substantive pledges."
"The damage will be in the billions of dollars," he said.
The United Nations has sent disaster assessment teams to the affected countries and relief organizations are distributing supplies. It is also starting to put together an appeal for international aid.
Worst hit have been Indonesia, Sri Lanka, Thailand and the Maldives. But Malaysia, Myanmar, Bangladesh, Somalia, Tanzania, Seychelles and Kenya have also been affected by the disaster.
"I have made big appeals in the past but this is unprecedented because very many countries are involved," Egeland said.
In Geneva Tuesday, U.N. officials met with governments, donors and aid organizations. On the same day U.N. ambassadors from some of the worst affected countries met Egeland in New York to discuss the disaster.
Sri Lanka's U.N. Ambassador Bernard Goonetilleke said the country's fishing and tourism industries - two mainstays of the economy - have been "practically devastated as a result of the tidal wave." He said his country desperately needed food, medicine and water purification tablets.
The Rome-based U.N. World Food Program said it has begun distributing food in Sri Lanka. Twelve truckloads were headed to the country's southern and eastern coasts, carrying about 185 U.S. tons of food, including rice, lentils and sugar, spokeswoman Caroline Hurford said.
UNICEF has already provided more than 30,000 blankets, as well as sleeping mats and clothing in Sri Lanka.
The International Committee of the Red Cross has sent medical supplies for about 120,000 people to the country to provide basic medical care and treat possible cases of diarrhea. A plane left Kenya Tuesday for Sri Lanka, carrying supplies for 50,000 people.
The Geneva-based U.N.-affiliated International Organization for Migration said it has also sent several truckloads of food, water and medicines to affected areas in Sri Lanka.
Mohamed Latheef, the Maldives' ambassador to the United Nations and the United States, said 130 of the country's 200 islands were substantially affected and 41 very seriously affected by the tidal wave.
Fourteen islands had to be evacuated and 19 inhabited islands have not been heard from. "Quite a few are underwater," he said.
The U.N. Office for the Coordination of Humanitarian Affairs (OCHA) is organizing an airlift - 15 tons of relief goods including tents, water containers, plastic sheeting, and emergency health kits - that is being paid for by the Norwegian government.
Indonesia's economic counselor Prayono Atiyanto said his country urgently needs food, body bags, fresh water, generators, medical supplies, blankets, mosquito nets, water buckets, clothing and beds.
There have been reports of looting by desperately hungry people in Indonesia. The United Nations in Jakarta said 175 tons of rice arrived in worst-hit Sumatra late Monday. The U.N. Children's Fund is preparing to fly in medical supplies, food for children, water purification equipment and material for shelter.
Thailand's U.N. Ambassador Laxanachantorn Laohaphan said the government's "wish list" includes forensic experts, body bags and a refrigerated mortuary.
The weekend tidal wave was the largest to hit Thailand, she said. "This is a big lesson for all of us, not only the countries in the region, but the whole world, that we should focus more on the prevention side."
In Somalia, which appealed for international relief on Monday, OCHA is organizing an aerial assessment of damage and U.N. agencies are preparing food for distribution.
By Leyla Linton