The United Nations mission in South Sudan has denied a report of a mass grave that was issued by the office of a UN commissioner for human rights.
The Berlin office of Navi Pillay had said on Tuesday that a grave of 75 bodies was found in Bentiu, Unity State.
Later the office revised that figure to 34 bodies and 75 people feared missing.
The UN mission in South Sudan (UNMISS) said the erroneous report was an inflation of a "skirmish" in which 15 people were killed.
'I have warned all responsible for crimes that they will be held accountable.' - Ban Ki-moon, UN secretary general
UNMISS said it is still deeply concerned about extrajudicial killings and is investigating those reports.
Ethiopian Foreign Minister Tedros Adhanom told The Associated Press that the leaders of six East African countries will travel to South Sudan on Thursday to try to advance peace talks and end 10 days of violence.
In a Christmas message to the people of South Sudan, UN Secretary General Ban Ki-moon emphasized that the United Nations "stands with the people of South Sudan at this difficult time."
"We know many of you are suffering from horrific attacks. Families are fleeing their homes. Many of you have lost loved ones and are grieving," he said in his radio and video message.
Ban called the situation in the country "a grave violation of human rights," but "South Sudan is not alone.
"I once again call on the country's leaders to settle their differences peacefully — and I underscore their responsibility to protect civilians.
"I have warned all responsible for crimes that they will be held accountable."