Aid efforts are failing millions of victims, the Red Cross and UN agencies declared at a briefing for diplomats in Geneva.
They repeated calls for 359 million euros to be donated, saying that so far only 115 million euros have been collected and a further 68 million euros promised.
World Bank chief Robert Zoellick on Friday warned of huge damage to crops.
“An early assessment is that the damages are more than in the earthquake in 2005,” he told a news conference while visiting Latvia. “The rough estimate is that there is a billion dollars of losses of crops. All of us will have to pitch in to help.”
Zoellick added that 700,000 homes are believed to have been destroyed or seriously damaged.
Between 15 million and 20 million people have been directly or indirectly affected, according to the International Committee of the Red Cross and Red Crescent although officials admit that they do not know the full scope of the disaster.
"There are millions of people needing food, clean water and medical care and they need it right now. Coordination is fine, action is even better," said Jacques de Maio, head of operations for South Asia at the International Committee of the Red Cross at the Geneva meeting.
The UN’s World Food Programme says that it has enough food to supply six million people for one month.
The International Organisation for Migration is aiming to provide emergency shelter for 300,000 families – about two million people.