A senior U.N. official has described the Indian Ocean earthquake and tsunami as among the worst-ever natural disasters.

As death and damage estimates soared, U.N. emergency relief coordinator Jan Egeland said there is still no way to gauge the scope of the tragedy. But he said it is unprecedented.

"What we can see is that a very, very major, perhaps one of most devastating natural disasters ever is confirmed," he said.

Mr. Egeland pointed to parts of Indonesia and the island nation of Maldives as areas about which nothing is known.

"Several areas have not yet been assessed or even visited. This is along the Sumatra coastline. There are islands in Maldives that no one has had access to since the tsunami hit," said Mr. Egeland.

Maldives is made up of more than 1,200 islands off the southern coast of India. Maldivian Ambassador Mohammed Latheef says some of the islands may have been washed away forever.

"Being very small islands, they washed away very quickly. Quite a few were under water. Nineteen islands. These islands are scattered on 90,000 square kilometers…so logistics and communication is very difficult in the Maldives," said Ambassador Latheef.

Emergency relief coordinator Jan Egeland and a team of U.N. aid experts met ambassadors of half a dozen countries Tuesday to begin prioritizing aid deliveries.

Afterward, he predicted that the appeal for international help would be the largest ever made by the world body because so many countries were hit.

The list of needy countries had been expanded to 10 with the addition of two African countries, but Mr. Egeland said he is encouraged that many of the hardest hit countries appear to a great degree to be able to take cope on their own.

"Some of the countries are coping themselves very well, which means we can concentrate on four or five of the about 10 countries affected. Somalia is a country we did not expect to have big damages. It is. There are many villages wiped away in poor Somalia," he said.

Mr. Egeland said international response to the disaster has been, in his words "overwhelmingly positive." He said much of the aid is being directed at the water and sanitation sectors in the worst-hit countries.

Indonesian diplomat Prayono Atiyanto told reporters his country's most urgent needs include body bags, fresh water, mosquito nets and water buckets, as well as food, especially baby food, and medicine.

But nearly 72 hours after the tsunami struck, Mr. Atiyono admitted he has no idea of the scope of the tragedy. Pressed by reporters for an estimate of his country's needs, his voice faltered as he said "We're still waiting."