The UN has accused South Sudan government forces and allies of killing 232 civilians and raping 120 women and girls in opposition-held villages.
A UN investigation identified three commanders suspected of bearing the “greatest responsibility” in the violence in Unity State between April 16 and May 24 that may amount to war crimes, the UN said.
“The perpetrators …must not be allowed to get away with it,” said UN High Commissioner for Human Rights Zeid Al-Hussein.
The investigation has also identified three individuals who may bear the greatest responsibility for the violations committed. One of them was reportedly removed from his functions for his alleged implication in these violations.
The violence took place after clashes between the SPLA and associated forces, and SPLA-IO (RM) in Unity State culminated in a significant military operation by Government and associated forces between April and May in multiple areas in southern Unity.
The military offensive was part of a broader cycle of violence in which opposition forces also carried out armed attacks resulting in civilian casualties.
Civilians were targeted, with the elderly, people with disabilities and very young children killed in horrific acts of violence – some hung from trees and others burned alive in their homes, the investigation found.
Victims and witnesses described how SPLA and aligned forces would storm into villages in the early morning or around dawn, surround the village and start shooting at fleeing civilians.
The attackers would then steal cattle, loot entire households and burn down houses and food stocks.
The report documents the use of sexual violence as a weapon of war, with at least 120 women and girls raped or gang-raped, including children as young as four.
The UN said the brutality and ruthlessness of the attackers, as described by survivors, suggests their intent was to take a “scorched-earth” approach, killing or forcibly displacing people, burning their crops and homes, punishing and terrorising them to ensure they never return.
Many fled under attack by gunfire and shelling.
“Some corpses seen by human rights monitors in villages in Northern Mayendit on 12 May exhibited bullet wounds in their backs,” the report states.
“According to information received, the elderly, sick and persons with disabilities who were unable to flee, were often burnt alive, as the attackers set ablaze their tukuls with lighters.”
As a result, 5,000 sought sanctuary at UN protected sites in Leer and Bentiu.
The UN said another 8,000 are estimated to be hiding in bushes and swamps while 18,000 have sought refuge in Mayendit town.
The UN added that humanitarian actors were also targeted.
Three local aid workers were killed and facilities destroyed, leaving vulnerable people without desperately needed food, water, medicine and shelter.
Mr Al-Hussein called on the government to halt all attacks against civilians, launch investigations and hold the perpetrators accountable, including those who bear command responsibility.
“The perpetrators of these revolting acts against defenceless civilians, including those bearing command responsibility, must not be allowed to get away with it,” High Commissioner Al-Hussein said.
“There must be consequences for the men who reportedly gang-raped a six-year-old child, who slit the throats of elderly villagers, who hanged women for resisting looting, and shot fleeing civilians in the swamps where they hid.
Those who ordered and facilitated these horrific crimes must be brought to account.
The Government of South Sudan and the international community have the obligation to ensure justice.”
Mr Al-Hussein called on the Transitional Government of National Unity in South Sudan and the African Union to move quickly towards establishing the Hybrid Court for South Sudan to ensure accountability for gross human rights violations.
He said the UN Mission in South Sudan and humanitarian actors are taking action on a number of fronts, including increasing the peacekeeping presence in the area, providing aid to those in need, continuing to monitor and report on human rights violations and carrying out political engagement with Government officials, commanders of both forces, and civil society.