Five million people in 11 countries lack the basic requirements for life

The death toll from the south Asian tsunami is likely to surpass 100,000, aid agencies warned yesterday as the first consignments from the biggest relief operation in history began to arrive to help survivors in the devastated region.

The United Nations said at least £1bn in emergency aid was needed after it calculated that the Boxing Day disaster left up to five million people across 11 countries without access to the basic requirements for life - water, food and sanitation.

Other aid agencies said that four days after the earthquake deep under the Indian Ocean, it was clear that the international community must now cope with death on a vast scale.

Simon Missiri, head of the International Federation of the Red Cross (ICRC) in the Asia Pacific region, said: "We're facing a disaster of unprecedented proportion in nature. We're talking about a staggering death toll." Scenes in the remote areas such as the west coast of Indonesia's Aceh province, closest to the quake's epicentre, were apocalyptic. Authorities there said it was now apparent that the entire population of some towns had been lost.

A UN official warned that up to 80,000 people in the province could have been killed amid reports of convoys of trucks dumping 1,000 bloated bodies at a time into open graves. Major General Endang Suwarya said: "The damage is truly devastating; 75 per cent of the west coast is destroyed and in some places it's 100 per cent."

Officials at the United Nations in New York said an appeal would be launched this weekend after relief assessments had been completed across the disaster zone.

In London, the British Government pledged £15m in immediate aid while the US President, George Bush, announced an international coalition with India, Japan and Australia to co-ordinate relief.

Tony Blair said in a New Year statement from Egypt, where he is on holiday, that Britain would do anything it could to help the affected countries. "This New Year the world is united in sorrow for those affected by one of the biggest natural disasters in our lifetime," he said. "Our thoughts are with those who have died, those who have lost loved ones and friends and those whose lives have been destroyed by this terrible catastrophe."

Stung by criticism from one UN official that the financial contribution of major nations was "stingy", Washington said it was more than doubling its initial donation to $35m (£19.4m).

Mr Bush said the eventual US response would far outstrip that sum: "We will prevail over this destruction," he said.

The World Health Organisation said the number of unburied bodies in the affected countries, from the five-star resorts of Thailand to impoverished villages of Somalia, along with the destruction of basic infrastructure, had left millions vulnerable to disease, which was likely to break out within three days.

David Nabarro, the head of the WHO's health crisis team, said: "Perhaps as many as five million people are not able to access what they need for living. Either they cannot get water, or their sanitation is inadequate or they cannot get food."

UN officials warned the eventual total required in relief funding was likely to outstrip the $1.64bn (£911m) raised for Iraq last year.

But as pledges flooded in, there were signs of a large gap between the requirement and reality. The total pledged by governments around the world last night stood at £126m.

Across the world, the public were also being implored to dip into their pockets.

Today The Independent launches an appeal urging readers to contribute to the vast amount of aid urgently required. The appeal is backed by the Foreign Secretary, Jack Straw, who said: "Whatever the Government can do, there is always an important role for personal donations and commitment."

The Independent appeal is being launched in association with the Disasters Emergency Committee, a coalition of 12 British-based charities, which said last night that £5m had been raised over 24 hours even before the official launch. The charities under its umbrella are ActionAid, the British Red Cross, Cafod, Care International, Christian Aid, Concern, Help the Aged, Merlin, Oxfam, Save the Children, Tearfund and World Vision.

Yet the relief effort seems to have been slow in coming. Across Asia, local volunteers were doing their best to provide help for the estimated five million left homeless while they waited for the much-needed international assistance.

As the aid operation began to swing into top gear with four plane loads of aid arriving in Sri Lanka from Britain, Germany and Japan, the need for the relief in this truly global disaster became ever more clear.

The official death count across Asia and Africa stood at 76,682 but aid officials made it clear that number would rise significantly as remote areas were reached, including India's Andaman and Nicobar islands, where one official said 10,000 were dead on one island alone.

Peter Rees, the ICRC's operations support officer, said: "The figure's going to be absolutely enormous. I would not be surprised that we are over 100,000 dead."

As the grim tally mounted, the Foreign Office said 26 Britons had been confirmed dead. That number was likely to increase beyond 50 after the Thai authorities said they were aware of at least 43 British nationals among 473 foreign tourists killed in its resorts.

Sweden, whose citizens have long viewed Thailand as a winter refuge, said 2,000 of its nationals remained missing. Germany said 1,000 tourists were unaccounted for.

But it was those living around the Indian Ocean who were dealing with the worst of the disaster.

According to ICRC estimates, there are 500,000 injured people across the region, 200,000 with serious injuries. In Sri Lanka alone there are a million people without shelter.

One aid worker for Cafod described the scene in Banda Aceh, the capital of Aceh province, as: "Corpses, corpses and more corpses. Walking on foot in the streets, it is all corpses. There is a rotten smell everywhere. Because people drowned, their stomachs are full and today they started to tear open.

"Right now there are many traumatised people. People scream 'water, water' while running. But there is no water. We can see people eating quietly next to dead bodies that are rotten and smelly. Many people cry hysterically."

The Indonesian government said one of its main shortages was providing sufficient body bags to contain the dead as the first aid supplies - 175 tons of rice and 100 doctors - reached Aceh province.

In Thailand, the government admitted it had been ill-prepared for the disaster and that it had been too slow to provide search equipment and refrigerated containers to store decomposing bodies to combat the spread of disease.