The world should expect to have to cope with three to five big urban disasters in the next 10 years, the Disasters Emergency Committee (DEC) has warned.
It said preparation for these disasters was needed now and revealed that the catastrophes aid workers feared most were earthquakes affecting Tehran in Iran, Istanbul in Turkey or Kathmandu in Nepal.
The report was commissioned following the devastation caused by the Haiti earthquake last year which killed more than 300,000 people.
Working closely with local traders, businesses, communities and government following such disasters was particularly important, the report said.
It also suggested prioritising support for permanent resettlement in existing neighbourhoods, rather than focusing on working in camps or providing temporary shelter.
The 950 million people now living in urban slums would be particularly vulnerable during any disaster.
The DEC said the report's conclusion, which suggested greater emphasis should be placed on longer-term ways of working, presented potentially tough choices for aid workers.
These could involve withdrawing free aid to temporary camps sooner after an urban disaster in order to work with local businesses to provide services and support that would speed up the safe return of survivors to their old neighbourhoods.
DEC chief executive Brendan Gormley said: "It is challenging to be told that after an urban disaster, we may need to give away fewer goods and services while doing more to support entrepreneurial and market solutions, but this is not a conclusion we can afford to ignore."