Rights group Human Rights Watch (HRW) said the African Union, European Union and the United Nations should impose tough sanctions on key figures in the government and in the rebel faction.

The 52-page report accused nine commanders of killing, rape and forced displacement of civilians. Most of the atrocities cited in the report were committed in 2016 in the Greater Equatorial region.

Seven top army generals, including President Salva Kiir, and two rebel generals, including rebel leader Riek Machar, are on HRW's list of individuals it wants sanctioned. According to the rights group, they are responsible for the worst atrocities being committed in the country's bloody civil conflict. 

Former army chief of staff, Paul Malong Awan, and Johnson Juma Okot, who was in charge of commanding government forces in former Eastern Equatorial, are also on the list. On the rebel side, Johnson Olony, who commands rebel forces in the Upper Nile region, is accused of forcefully recruiting child soldiers.

Government and rebel forces deny HRW accusations

Both factions have denied any responsibility for the atrocities.

"A number of government individuals may have committed crimes by taking the laws into their own hands," said Ateny Wek Ateny, spokesman for President Kiir, "but that doesn't mean the government has a policy of killing civilians."

Witnesses interviewed by HRW said in most cases government soldiers entered their homes and shot civilians including elderly and people with disabilities.

"The president is doing his best and that report should have acknowledged what the president has been doing. The president has issued amnesty and unilateral ceasefire," Ateny added.

"Our chairman Dr. Riek Machar is innocent [of these crimes]," said General Nathaniel Oyet, senior politician of the rebel's SPLM-IO political wing. Oyet said it was wrong to accuse Machar of the atrocities being committed in South Sudan.

"[Machar] is a victim of human rights [abuses] himself. He cannot be sanctioned together with perpetrators like Salva Kiir and his government that deserve sanctions. They blocked the peace agreement, they allowed it to collapse and now they are carrying out military offences against IO forces. We are simply defending ourselves," Oyet said.

Crimes against civilians?

Government soldiers deployed to fight rebels in counter insurgency operations are accused of committing a range of crimes against civilians on the basis of their ethnicity, arbitrary detention, torture and widespread looting.

The report cited atrocities committed in mid-2016 in Kajo-Keji county. HRW said attacks started in the area after the deployment of government troops. At least 47 people were killed unlawfully by government soldiers between May and June 2017, according to the rights group.

HRW wants the Commission on Human Rights in South Sudan to launch an investigation into criminal responsibility of the nine generals - both direct and on the basis of command responsibility. They called for an establishment of a hybrid court proposed in the 2015 peace agreement in order to deal with such cases.