Tens of thousands of people in western South Sudan have been forced to flee killings, gang-rape, torture and other abuses by government soldiers, leaving entire neighbourhoods empty, Human Rights Watch (HRW) says.
It said South Sudanese soldiers were "getting away with murder" and called for the government to halt abuses and support the creation of a war crimes court to investigate and prosecute perpetrators.
Attacks on Fertit civilians in and around the town of Wau in the Western Bahr el Ghazal region surged in December following a deployment of soldiers from the Sudan People's Liberation Army (SPLA) to the region, HRW said on Tuesday, adding that most were from the Dinka ethnic group.
The soldiers looted and burned down homes and unlawfully detained Fertit men, HRW said. The abuses continued into the spring despite the local authorities reporting the attacks to the army and government officials, it added.
"With all eyes on the new national unity government in Juba, government soldiers have been literally getting away with murder in the country's western regions," HRW's Africa director Daniel Bekele said in a statement.
The rights group said the SPLA had denied the accusations in a letter received this month. Residents reported that soldiers were moved out of positions in and around Wau in early May, HRW added.
A spokesman for the South Sudan government was not immediately available for comment.
Fighting erupted in the country in December 2013 when President Salva Kiir sacked his first vice president Riek Machar, triggering ethnically charged clashes that the United Nations says have killed thousands and forced more than 2.3 million to flee.
Under pressure from the United States, the United Nations and other powers, both sides signed a peace deal in August, but it broke down repeatedly.
Kiir named a new "national unity" cabinet in late April, including former rebels and members of the opposition, after Machar returned to Juba and regained his old job.
HRW researchers who visited Wau in April said several Fertit neighbourhoods remained largely empty.
"They collected our things and burned our houses," a 42-year-old man told HRW, describing an attack by some 30 soldiers on Ngumba village.
"Those who resisted or could not move were killed. My grandmother tried to flee and was shot just outside the hut."