The UN has expressed its fears that a report on South Sudan's civil war will be not discussed during the African Union (AU) summit in Ethiopia's capital Addis Ababa at the end of January.
The report, which was commissioned by the AU, details the atrocities committed during the conflict, which erupted in South Sudan in December 2013.
UN Assistant Secretary General Ivan Simonovic said the report would be a "very disturbing development".
"We think it's essential to have that report submitted during the African Union summit, but also to make that report public afterwards," he was quoted by AFP as saying.
The South Sudan conflict erupted when President Salva Kiir, from the Dinka ethnic group, accused then vice-president Riek Machar of plotting to overthrow the regime.
The accusations sparked violence in the country, where factions loyal to Kiir and Makar engaged in tit-for-tat violence that has claimed thousands of lives.
At least four million people are also at risk of a man-made famine, due to lack of funds and widespread fighting which has stopped volunteers reaching certain areas.
As the civil war entered its second year in December, human rights activists warned the conflict was far from over and the country has experienced a "colossal loss of life".
On the anniversary of the country's civil war, activists published lists with the names of 10,000 casualties, which included "farmers, traders, men in uniform, including UN peacekeepers, but the majority of the victims on the list are civilians and young people, demonstrating that South Sudan has lost so much of its human capacity and potential".
UN secretary-general Ban Ki-moon, who is to attend the AU summit on 29-31 January, said the crisis was "tragic and unacceptable" as he urged South Sudanese leaders to reach an agreement and end the fighting.