UN humanitarian chief Jan Egeland has called on African, Arab and Asian countries to urge Sudan to accept a UN peacekeeping force in Darfur
Speaking in Geneva, Mr Egeland called the Darfur conflict a nightmare which continued to get "worse and worse".
He also welcomed comments by Nigerian President Olusegun Obasanjo who warned of a possible genocide in the region.
Sudan has consistently rejected plans to send UN peacekeepers to replace an undermanned AU force in Darfur.
"Help us, because we are desperate here," Mr Egeland told reporters in Geneva.
"We are hanging on by our fingernails. The relief operation could crumble at any moment," he warned.
Mr Egeland also told the BBC that the UN may have made a diplomatic mistake in allowing Western countries to take the lead in applying pressure on Sudan to agree to a UN force.
"You have to have a heart of stone to not understand the situation of the women and children of Darfur," he added.
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