NAIROBI, Kenya -- The United Nations mission in South Sudan has denied a report of a mass grave that was issued by the office of a U.N. 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 U.N. mission in South Sudan said the erroneous report was an inflation of a "skirmish" in which 15 people were killed. UNMISS said it is still deeply concerned about extrajudicial killings and is investigating those reports.

Ethiopia Foreign Minister Tedros Adhanom told The Associated Press that the leaders of six East African countries will travel to South Sudan Thursday to try to advance peace talks and end 10 days of violence.