The U.N. peacekeeping force in South Sudan said cattle thefts and demands for bridal dowries are stoking ethnic tensions in the border state. Surveillance by peacekeepers last week revealed signs that rival ethnic militias may be preparing for major conflict.
U.N. Secretary-General Ban Ki-moon, in a statement issued through his spokesman, said national security was the top concern for a newly independent South Sudan.
"The secretary-general calls on the leadership of both groups to cease violence and to work with the government toward a long-term solution to the root causes of the hostilities," the statement read.
Residents in Jonglei reported armed militants went on a killing spree and stole cattle from their community earlier this month.
The U.N. peacekeeping mission for South Sudan reported that around 45 people were killed and many others fled the area following the attacks. At least 1,000 people have been killed this year in ethnic clashes in South Sudan, the U.N. mission there said.