The government says it is not prepared for the humanitarian impact of the vote.
Minister of Humanitarian Affairs and Disaster Management James Kok said Tuesday that the south needs aid to cope with the 1.5 million southerners now living in the north who might return home. Kok says thousands of Sudanese living in neighboring countries could also return.
Kok says a third possible scenario would see the north and south return to war.
A U.N. official, Lise Grande, said donors have been very generous with Southern Sudan but said many people in the south still suffer.