0102 GMT January 20, 2018
The UN human rights office on Friday also accused the pro-government troops of committing other human rights violations and abuses in and around Yei, including uncounted rapes and torture.
"Attacks were committed with an alarming degree of brutality and, like elsewhere in the country, appeared to have an ethnic dimension," said a report on the findings of an investigation conducted by the UN.
According to the report, the abuses included attacks on funerals and “indiscriminate shelling of civilians.”
South Sudan's army spokesman Colonel Santo Domic Chol Juba condemned the report as "baseless."
"This is not the first time the UN has accused the SPLA and tried to portray us as enemies of the people," he said, referring to the Sudan People's Liberation Army (SPLA).
“The SPLA is one of the biggest military institutions in the country and it accommodates people from different background and the whole SPLA cannot go out and rape citizens... so it has to be specific that we have seen two or three SPLA soldiers in such location committing such crimes,” he said, adding that President Salva Kiir had given orders to punish soldiers who commit rape.
The report also exposed “cases of sexual violence perpetrated against women and girls, including those fleeing fighting.” They were reportedly often committed in front of the victims' families.
"Some of the human rights violations and abuses committed in and around Yei may amount to war crimes and/or crimes against humanity," the report added.
Civil war broke out in South Sudan in 2013, when disagreements between President Kiir and then Vice President Riek Machar turned into an armed conflict between their loyalists. While fighting generally subsided early last year, clashes once again intensified in July 2016.
Tens of thousands of people have died in the civil war, and more than three million people have been uprooted.
According to the report, violence engulfed the once peaceful town of Yei after government forces pursued Machar, who fled with a small group of his followers into the Democratic Republic of the Congo, through South Sudan's Equatorias region following July's clashes.
The pursuit led to the eruption of fighting along the route, especially in Yei, an ethnically diverse area by tradition, the report added.