Government forces commit war crimes in Unity - Rights Group

South Sudanese government forces attacked and killed scores of civilians, carried out public gang rapes and burned people alive during a recent military offensive in northern Unity State, a rights group said on Wednesday.

Government troops and allied militia launched a campaign in April against rebel forces in oil-producing Unity, in a civil war which broke out in December 2013 when a political crisis sparked fighting between forces loyal to President Salva Kiir and rebels allied with his former deputy Riek Machar.

The attacks on civilians and the widespread burning and pillaging of property in the recent offensive amount to war crimes, while the killings and rapes may also constitute crimes against humanity, according to Human Rights Watch (HRW).

"Brutal attacks on fleeing civilians combined with widespread burning of villages, food, and other items that people need to survive suggests that the government's aim was to forcibly displace people from their homes," HRW Africa director Daniel Bekele said in a statement.

South Sudan's presidential spokesman said the government categorically rejected HRW's allegations of human rights abuses, rapes and killing of unarmed civilians, and described the claims as "baseless".

If it came to light that government forces had perpetrated war crimes and crimes against humanity, they would be brought to justice, Ateny Wek Ateny told the Thomson Reuters Foundation by email.

HANGED, BURNED, CRUSHED BY TANKS

At least 60 civilians, including children and the elderly, were killed, according to the HRW report "They Burned It All", based on interviews with some 170 victims and witnesses.

Many were hanged, shot while trying to flee and burned alive, others were crushed by tanks, the rights group said.

"They were running with the tanks after the people, and then after they hit them they would roll back over them, to confirm that they were dead," one woman told HRW in the report.

Government soldiers and fighters from the Bul Nuer tribe repeatedly beat women, forced them to carry pillaged property and abducted them, the report said.

More than 60 women were raped in the offensive, including gang rapes by fighters, and only one survivor interviewed by HRW had received any medical assistance afterwards.

"Women and girls are bearing the brunt of this brutal offensive as fighters target them for rape, abduction, beatings and forced labour," Bekele said.

The attacks in Unity which lasted until mid-June left aid agencies struggling to reach tens of thousands of people who fled from towns and villages and remain isolated in rural, often swampy, areas without help.

Stephen O'Brien, who replaced Valerie Amos as the United Nations aid chief earlier this year, was scheduled to arrive in South Sudan on Wednesday to discuss the conflict and ways of strengthening the humanitarian operation.