United Nations Mission in South Sudan or UNMISS called on the fighting parties to accept Inter-Governmental Authority on Development or IGAD demands and immediately stop fighting.
UNMISS head Hilde F Johnson told the press in Juba on Wednesday that both parties should use the first day of the New Year to take a decisive step for peace and cease all hostilities.
She said there were killings and brutality, grave human rights violations and atrocities committed.
Ms Johnson strongly condemned atrocities committed against innocent civilians of different communities by elements from both sides.
She said all perpetrators must be held accountable, warning that if no one was held accountable there is a major risk that the violence continues.
UNMISS Chief said accountability was critical for reconciliation to happen to rebuild trust for the country to move towards peaceful relations.