Five major disasters expected within next decade
The world should be braced to expect three to five big urban disasters in the next 10 years, the Disasters Emergency Committee (DEC) warned.
It said preparation for these disasters was needed now and revealed that the catastrophes aid workers feared most were earthquakes affecting the large cities of Tehran in Iran, Istanbul in Turkey or Kathmandu in Nepal.
The report was commissioned following the earthquake in Haiti 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, rather than focusing on working in camps.
The 950 million people now living in urban slums would be particularly vulnerable.
The DEC said the report's conclusion presented potentially tough choices for aid workers.
These could involve withdrawing free aid to temporary camps sooner in order to work with local businesses to provide services and support that would speed up the safe return of survivors to their homes.
DEC chief executive Brendan Gormley said: "The Haiti earthquake presented our member agencies with one of the greatest challenges I have seen.
"Our member agencies are committed to continuous improvement and this means asking ourselves hard questions about the tough choices we face during an emergency."