The Red Cross has criticised aid agencies for failing to co-ordinate their response to the tsunami disaster.
There were thousands of bodies to recover after the Asian tsunami
Rivalries between hundreds of groups led to a duplication and in some places a delay in aid reaching those affected, the Red Cross said in a report.
It also said that tens of thousands of people who died would have survived if they were given quicker warnings.
The annual Red Cross survey also said the response to the well-predicted famine in Niger was insufficient.
Some 250,000 people died in disasters in 2004, 225,000 in the tsunami.
Disasters including floods, famine and hurricanes affected about 146 million people worldwide, according to the annual World Disasters Report by the International Federation of the Red Cross and Red Crescent.
The majority of those, about 110 million, were affected by severe flooding in India, Bangladesh and China.
The devastating death toll in the Asian tsunami skewed the official casualty figures, pushing the 2004 total way past the recent average of 67,000.
The international director of the British Red Cross told the BBC that 300 to 500 charities had arrived in Sri Lanka following the disaster, some of which had little or no experience.
"It is simply very complex and chaotic when a disaster like this strikes," Matthias Schmale said.
Correspondents say the scale of aid raised was partly to blame for a lack of co-ordination between agencies.
Mr Schmale said the UK agencies involved were established groups, like Oxfam, Save the Children and the Red Cross.
"In remote places... and in some cases, new charities were set up which simply showed up on the scene and tried to help," he said.
The report also said that scientists monitoring the Indian Ocean detected the giant earthquake off the coast of Indonesia, but had no way to alert people.
"Early warning is the most obvious way in which accurate, timely information alone can save lives," the organisation's Secretary General, Markku Niskala, wrote in the introduction to the report.
Months later, many affected areas now have tsunami warning systems
The report contrasted the lack of co-ordinated information about the impending tsunami disaster with the efficient warning systems in place when four strong hurricanes swept through the Caribbean during 2004.
A string of countries in the region issued evacuation orders and advised citizens on how to ride out hurricanes, minimising death tolls.
The report also focused on Niger, where warnings over poor harvests were not heeded by the international community.
"There were enough early warning signs to say that the situation could be quite severe in 2005," said Hisham Kigali, head of disaster response for the Red Cross.
"What as a humanitarian community we didn't do well enough is give out enough repeated messages saying that, particularly to donors."