Bjorn Liungqvist, the UN's acting humanitarian coordinator said the drought had mainly affected the country's livestock farmers due to a lack of rainfall.
In a statement he said: "The situation in the pastoral areas is most critical."
The UN says a shortage of rain in many parts of East Africa, including Kenya, Somalia and Ethiopia, has left around 6 million people on the brink of starvation.
Aid agencies say rural communities are worst hit by the drought as their survival depends on the climate, and the lack of rain across the three neighbouring nations has prevented them from using their normal coping mechanism: migration.
Liungqvist said the nomadic communities in the region were also threatened by the onset of disease.
"Malaria, measles and meningitis all require intense preventive interventions to control their threat," he said.
The region also faces the threat of floods, locust invasions and other disasters, and Liungqvist urged potential donors to act fast to prevent further tragedy.