NAIROBI, Kenya — Gang rape, the massacre of civilians and even instances of forcing captives to jump into fires and eat human flesh are among a long list of atrocities committed during South Sudan’s continuing civil war, according to a long-awaited report by the African Union.

The report, published late Tuesday but not widely available in eastern Africa until Wednesday, was written more than a year ago but was held back because African Union officials feared that it could complicate the on-again, off-again peace efforts for South Sudan, a fragile, destitute nation that exploded into ethnically driven violence two years after winning independence in 2011.

According to the African Union investigation, the government of President Salva Kiir, and rebels led by Riek Machar, the vice president he fired in the summer of 2013, both targeted civilians.

“The stories and reports of the human toll of the violence and brutality have been heart-wrenching,” the report said. “People being burned in places of worship and hospitals; mass burials; women of all ages raped, both elderly and young. Women described how they were brutally gang-raped and left unconscious and bleeding. People were not simply shot, they were subjected, for instance, to beatings before being compelled to jump into a lit fire.”