One of the world's largest relief efforts is under way to help the millions of victims of the Asia quake, as the death toll continues to mount.
Health experts fear disease could double the death toll
More than 50,000 people are now known to have died, but more bodies are being discovered every hour in many of the countries affected.
Sunday's undersea quake triggered sea surges that also displaced millions.
International disaster assessment teams are arriving and local agencies are distributing emergency aid.
But the disaster zone is now threatened with outbreaks of disease, which the UN health agency has warned could double the death toll.
Sri Lanka, Indonesia, India and Thailand were among the worst hit by Sunday's 9.0 magnitude earthquake, which sent huge waves from Malaysia to Africa.
The UN has said it faces an unprecedented challenge in co-ordinating distribution of aid to some 10 nations at once.
In several of those nations, some outlying towns and villages have not yet even been reached. But as rescue workers discover more bodies, the true extent of the tsunami's devastation is becoming clearer:
CONFIRMED DEATH TOLL
Sri Lanka: 18,706 dead
Indonesia: 27,174 dead
India: 4,371 dead
Thailand: 1,516 dead
Maldives: 52 dead
Malaysia: 44 dead
Burma: 30 dead
Bangladesh: 2 dead
Somalia: 100 dead
Kenya: 1 dead
Seychelles: 3 dead
Tanzania: 10 dead
- Indonesia's government says the country's death toll has reached 27,174
- Parliamentary elections in the Maldives, scheduled for Friday, are postponed, as a government official warns the cost of damage could exceed the island nation's annual GDP
- About 7,000 people are feared dead in the low-lying Andaman and Nicobar islands, say Indian officials, with 20% of the population on one island, Car Nicobar, believed killed
- The bodies of more than 700 mainly foreign tourists have been found in the Thai resort of Khao Lak - the government says the death toll in Thailand may rise to about 2,000.
UN emergency relief co-ordinator Jan Egeland said on Tuesday the organisation
would probably make its largest ever appeal for humanitarian funding.
He told the BBC that the damage was "beyond comprehension".
"A tsunami of this size happens once in a generation only," he said.
"The first wave of destruction has caused tens of
thousands of deaths, but the second wave of misery is
really caused now by the water and sanitation systems."
In Geneva, World Health Organization (WHO) expert David Nabarro told reporters "there is certainly a chance that we could have as many
dying from communicable diseases as from the tsunami".
Clearing the dead
In Sri Lanka alone, more than one million people are displaced and aid workers are under pressure to ensure they have clean water and sanitation to prevent an outbreak of disease.
The local UN agency has opened up its relief stockpiles, but the BBC's Roland Buerk says there is little sign as yet of aid supplies in the south-west town of Galle.
People in both Sri Lanka and in Indonesia have been scrambling through mud and ruins looking for food and water, correspondents report.
Mr Egeland said hundreds of planes carrying emergency aid would be airborne over the next couple of days.
Flights carrying emergency supplies from nine countries, including Britain, France and the US, were due to arrive in Sri Lanka on Tuesday.
Many tourists are among Thailand's dead
Coastal communities across South Asia - and more than 4,000 km away in Africa - were swept away and homes engulfed by waves up to 10m high after the quake created a tsunami that sped across the ocean.
Many of the victims had no warning. Fishermen were swept off boats, and tourists were washed from the beaches.
Sunday's tremor - the fourth strongest since 1900 - had a particularly widespread effect because it seems to have taken place just below the surface of the ocean, analysts say.
Tsunamis generated by earthquakes can travel at up to 500km/h.
IMPACT OF THE EARTHQUAKE