But last year he fled to Khartoum and started a rebellion against South Sudan's government in Pibor.

NPR: South Sudan Military Says 163 Killed In Clashes

Okello is in South Sudan's southeast Pibor County, where Yau Yau hails from.

NPR: South Sudan Military Says 163 Killed In Clashes

Besides General Athor, another losing candidate, David Yau Yau, is at large in Jonglei with hundreds of armed followers in Pibor, in the state's east.

ECONOMIST: South Sudan

He accused local politicians of exacerbating the long-standing rivalries for their own ends and also asked why UN peacekeepers and the army were protecting government buildings in Pibor, rather than people.

BBC: Jonglei clashes: South Sudan declares a disaster

Correspondents say that Jonglei has been hit by widespread ethnic violence since South Sudan became independent from Sudan in July 2011 - with much of it taking place in Pibor county, where the UN peacekeeping force is based.

BBC: Indian Unmiss solider in Jonglei

Earlier, John Boloch of South Sudan's Peace and Reconciliation Commission and a member of the Murle community, said people who had fled Pibor had since been hunted down and killed near the River Kengen, south-east of the town.

BBC: Jonglei clashes: South Sudan declares a disaster

Aguer said the southern military, known as the SPLA, would continue to "deal with the militia group" and that it would be a matter of time before the rebels are cleared from Pibor County in the state of Jonglei.

NPR: South Sudan Military Says 163 Killed In Clashes