Addis Ababa - A top African Union official who led an inquiry into atrocities in war-torn South Sudan warned on Friday that ignoring its recommendations would help the guilty to evade justice.
Amnesty International and Human Rights Watch also said keeping the report under wraps would only benefit those trying to avoid possible war crimes trials.
Led by former Nigerian president Olusegun Obasanjo, the AU commission of inquiry spent six months last year investigating the tens of thousands slaughtered in the civil war between fighters loyal to South Sudan President Salva Kiir and his sacked deputy-turned-rebel leader Riek Machar.
Cycle of impunity
Mandated to "investigate human rights violations and other abuses during the conflict by all parties", Obasanjo handed over its findings on Thursday to the AU's Peace and Security Council, but its recommendations have not been released.
"The peace process and the mandate of the Commission of Inquiry are two sides of the same coin," Obasanjo told reporters on Friday.
"The cycle of impunity must be broken... we urgently hope that the recommendations of the report will be implemented."
Fighting broke out in South Sudan, the world's youngest nation, in December 2013 when Kiir accused Machar of attempting a coup.
Also read: AU supports regional task force to fight Boko Haram
The fighting in the capital Juba set off a cycle of retaliatory massacres across the country, pushing it to the brink of famine.
Six ceasefire deals have all collapsed, with rivals due to meet again for the latest peace effort on Saturday alongside leaders of East Africa's regional bloc IGAD.
A petition from 21 key South Sudanese civil society organisations called for the report to be made public, saying it could play a "critical role in deterring further violations" as well as "ensuring accountability for crimes committed".
Amnesty International spoke of a "slap in the face" for those who had risked giving evidence to the commission, and that the AU had "failed the thousands of South Sudanese victims who are waiting for truth and justice."Strike a deal
Human Rights Watch warned that suppressing a report "documenting wartime abuses... could hinder bringing those responsible for war crimes and crimes against humanity to account."
UN Secretary General Ban Ki-moon, speaking earlier on Friday at the opening of the annual AU summit, called on Kiir and Machar to strike a deal to "end this man-made tragedy."
Obasanjo had said when he started his investigation that "Africa must not condone impunity of Africans treating Africans as if they are not human beings," and that he would "leave no stone unturned."