Deaths were also reported in Bangladesh, Malaysia, the Maldives, Myanmar and distant Somalia where 38 people were killed by swollen seas. The earthquake triggered a tsunami of up to 10 metres high, sometimes travelling as fast as an airliner, flattening houses, hurling fishing boats onto roads, sending cars spinning through swirling waters into hotel lobbies and sucking sunbathers, babies and fishermen out to sea.

As survivors were evacuated from stricken areas across Asia, the full horror of carnage wrought by the tidal waves emerged; babies torn from their parents' hands, children and the elderly hurled out to sea from their homes, entire villages swept away.

The quake, the fourth largest recorded since 1900 at 9.0 on the Richter scale, occurred after a rupture on the Indian Ocean seabed caused by the violent grinding of two tectonic plates, killing at least 23,675 according latest official figures.

Sri Lanka and India were severely hit with respective death tolls of 11,000 and 6,823, while the number of dead in Indonesia rose to 4,725. A further 866 deaths were reported in Thailand, 56 in Myanmar, 52 in the Maldives, 51 in Malaysia and two in Bangladesh.

Huge waves swept about 7,000 kilometres as far as Africa, crashing on to the shores of Kenya and Somalia, affecting the islands of Mauritius, Reunion and the Seychelles on the way. More than 100 Somali fishermen were confirmed dead.

The United Nations said the international response to the disaster would have to be bigger than the one mounted a year ago when a quake killed about 30,000 people in Bam, Iran.

"The cost of the devastation will be in the billions of dollars. It would probably be many billions of dollars," said Jan Egeland, the UN under-secretary general for humanitarian affairs.

"We had then the biggest outpouring of international relief ever. I think we will have this one surpass that and it should because it's a much bigger disaster," he said.

Indonesia's Aceh province bore the brunt of the temblor, hit at point-blank range and then battered by a tsunami, leaving at least 4,725 dead and many more missing. An AFP reporter among the first to reach the province's main city Banda Aceh, which has been in blackout since the quake struck, described a scene of death and ruin, with hundreds of bodies and pulverised buildings.

Bloodied corpses covered by plastic sheets lay rotting on the ground at an Indonesian Red Cross office in Lambaro. Police said there were 500 bodies at the centre. "People told me it was as if God had unleashed his anger on the people," said Haji Ali, a resident in Patong Labu, a small settlement close to the north Aceh town of Bireuen.

Relief efforts have been hampered by the closure of the region's main airport at Banda Aceh. In Sri Lanka a massive humanitarian operation was launched to help 375,000 people believed to have lost their homes.

"We had no mechanism to deal with this type of disaster," said top government aide Lalith Weeratunga, as the nation appealed for international aid and President Chandrika Kumaratunga declared a state of disaster.

In southern India survivors grimly buried or burnt their dead as the death toll rose to more than 6,500, with thousands more missing amid warnings of a return of killer tsunamis.

In the worst-hit Indian state Tamil Nadu, fisherman A. Ravi wept as he recalled watching his family, including four children, swept away as his village was flattened.

"We went fishing in the early morning and a few hours later the water started swirling around us and suddenly the level went down so sharply we could see the seabed," said Ravi.

"Then I saw a huge sheet of water going towards the shore... when I got back I found my village under water and my family gone," he said. The Indian death toll included about 3,000 in the Andaman and Nicobar Islands, close to the temblor's epicentre where tens of thousands of people were still unaccounted for.

The death toll in Thailand, where a further 1,200 were listed as missing, included scores of foreign tourists and a grandson of King Bhumibol Adulyadej, with more than 7,300 injured.

Almost 29,000 people were evacuated from the worst affected areas, which included the resort islands of Phuket and Phi Phi where thousands of European tourists had been enjoying holidays.

Hardly a building was left standing on Phi Phi island east of Phuket, where bodies were seen strewn about the island, covered in white cloths before being taken away by emergency crews and volunteers.

"I saw bodies almost everywhere on land, and in the water too, and I think there are many more bodies trapped under the bungalow debris," said rescuer Wirat Mansa-ad, estimating 300 died on the island alone.

As Thailand mobilized its army and navy in a huge rescue operation, dazed foreigners began flying home - still struggling to come to grips with what had happened. Just before the first wave struck, "there was no water left in the ocean. The fish were just flapping and dying on the beach," Danish tourist Svend Falk-Roenne, 52, told AFP in Bangkok on his way home from Phuket.

"Then the wave just came towards us. I've never seen anything like it." Melina Heppell, a six-month-old baby girl from Australia, was swept from her father's arms on Patong Beach, Phuket, when a tsunami wave hit, her uncle Simon Illingworth said on Australian television.

"They were walking along Patong Beach yesterday... he thought he had the baby in his hands, but all he had was clothes," Illingworth said, tears streaming down his cheeks.

The United Nations rushed disaster teams to south and southeast Asia, saying hundreds of thousands of people in coastal areas were at risk, with livelihoods from fishing and farming wiped out and disease threatening to wreak more havoc.

Governments from France to Australia and Russia to the United States pledged aid and assistance, despatched aircraft, doctors and disaster relief specialists to the worst-hit areas.

"The power of this earthquake, and its huge geographical reach, are just staggering," said Carol Bellamy, executive director of UN Children's Fund (UNICEF). "Hundreds of thousands of children in coastal communities in six countries may be in serious jeopardy," she said.

In Geneva, the International Federation of Red Cross and Red Crescent Societies appealed for 7.5 million Swiss francs (4.8 million euros, 6.6 million dollars) to help an estimated 500,000 survivors.

In Malaysia, 51 people, including many elderly and children, were drowned and many others were missing after tidal waves hit the resort islands of Penang and Langkawi and the north western coast.

On the Indian Ocean tourist paradise of the Maldives, two British tourists and 50 other people died while 68 people were missing after tidal waves lashed and flooded the low-lying island chain, officials said. -AFP/Reuters