South Sudanese soldiers and rebels have executed people based on their ethnicity, Human Rights Watch said Thursday, as fears mount that days of heavy fighting could spiral into civil war.
Hundreds of people have been killed and thousands more terrified civilians have fled their homes to seek protection at UN bases since the fighting broke out on Sunday in the capital Juba.
"Soldiers in Juba sometimes asked individuals about their ethnicity before killing or releasing them, or identified them from facial scarification," HRW said quoting witnesses.
Many South Sudanese traditionally wear tribal scarring on their faces and bodies.
"We are deeply concerned that ethnically-based attacks on all sides will lead to revenge attacks and more violence," HRW's Africa director Daniel Bekele said in a statement.
President Salva Kiir has blamed the bloodshed on an attempted coup bid by his arch-rival and former deputy Riek Machar, who is now on the run, with troops loyal to him seizing the key town of Bor.
The battles have raised fears of ethnic conflict, with Kiir coming from the majority Dinka people and Machar from the Nuer.
South Sudan's government has repeatedly said the fighting is over politics, not ethnicity, but HRW's report detailed multiple cases where civilians were killed due to their tribe alone.
"Government soldiers... and police questioned residents about their ethnicity and deliberately shot ethnic Nuer," HRW said, quoting reports from witnesses and victims.
There are also "reports that ethnic Dinka may have been targeted in Juba and in the town of Bor by Nuer soldiers", HRW added.
Army spokesman Philip Aguer said Thursday some 450 people had been killed in Juba since battles broke out late on Sunday, but added that troops had "restored calm" in the capital of the world's youngest nation.
One woman in Juba told HRW she saw armed men from both Dinka and Nuer tribes "moving from house to house apparently searching for members of the other ethnic group".
In one of several cases listed, another man described how soldiers executed seven Nuer men hiding in a compound in Juba's western Gudele district, describing how one had "hid in a water barrel and was killed in there."
Civilians have also been killed in crossfire, while residents described two cases in which tanks drove into houses, with witnesses describing seeing bodies crushed after being run over.