Uganda fights in South Sudan as UN decries atrocities

Juba (AFP) - Uganda confirmed its troops are fighting alongside South Sudan's government against rebels as a UN envoy decried atrocities committed by both sides.

Ceasefire talks -- to end the conflict of over a month in which thousands have been killed -- are deadlocked amid squabbling leaders and rebel demands for the release of political prisoners.

A UN rights envoy in South Sudan said Thursday he had seen bodies in the streets that had been tied before being shot as the global body stepped up warnings over rights abuses.

The UN has accused both sides of carrying out atrocities in the conflict that started on December 25.

Amid mounting reports of mass killings in several towns, UN assistant secretary general Ivan Simonovic said 92 UN investigators were in the country and a first report would be released in about two weeks.

Speaking in New York after a visit to the Unity state capital of Bentiu, Simonovic said it had been left a "ghost town" by successive raids by the rival forces. Nearly all the 40,000 inhabitants have fled.

"When there is change of control over Bentiu each time the group that was taking control was involved in human rights violations including killings of civilians," Simonovic was quoted as saying by the UN mission in South Sudan.

"We could see about 15 to 20 decomposing bodies just by the street," he added. "Obviously civilians are being tied before being killed."

UN leader Ban Ki-moon has warned that both sides will be held accountable.

Up to 10,000 people are believed to have been killed so far in the fighting pitting forces loyal to President Salva Kiir against a loose coalition of army defectors and ethnic militia nominally headed by Riek Machar, a former vice president and seasoned guerrilla fighter.

'Widespread killings'

Human Rights Watch (HRW) said in a report released Thursday that it had interviewed witnesses to abuses in the capital Juba and Bor.

It said there had been "widespread killings" of ethnic Nuer men by Kiir's armed forces in Juba, including a massacre of between 200 and 300 men in the Gudele neighbourhood on December 16.

The group has also taken evidence of targeted killings including the shooting of children.

"They brought out five of my neighbours and shot them in the street," a 42-year-old bricklayer in Juba told HRW, recounting killings at the start of the conflict.

Meanwhile government delegation head Nhial Deng Nhial arrived back in Juba calling the negotiations in neighbouring Ethiopia "tough" and that he had come to consult back in the capital.

The talks are mediated by the East African regional bloc IGAD, of which Uganda is a key member, raising concerns for the body as a neutral negotiator for the rebels.

Ugandan President Yoweri Museveni said his troops were supporting the Sudan People's Liberation Army (SPLA) -- the first official confirmation foreign forces are taking part in combat.

"The SPLA and elements of our army had a big battle with these rebel troops... we inflicted a big defeat on them," Museveni said, speaking in at a summit meeting in Angola late Wednesday.

"Unfortunately, many lives were lost on the side of the rebels. We also took casualties and also had some dead."

A confidential memo from Kenya's foreign ministry seen by AFP reports that Machar has alleged Ugandan fighter jets have tried to bomb his hideout in Jonglei state.

The document warned the presence of foreign forces -- also reportedly including rebel fighters from neighbouring Sudan's Darfur region -- could "derail the process" of talks, with Machar telling Kenya that "the credibility of IGAD as a mediator in the conflict is in question".

According to the United Nations, some 400,000 civilians have fled their homes over the past month as the violence spiralled into ethnic killings between members of Kiir's Dinka people -- the country's largest group -- and the Nuer community of Machar.

UN leader Ban has expressed alarm at the "rising number of fatalities" in the fighting and condemned both the army and rebels for stealing food and humanitarian supplies.

The UN World Food Programme has said enough food has been stolen to feed 180,000 people for a month.

More than four million people, or roughly a third of the population of the country that won independence from Sudan only in 2011, were deemed to be "food insecure" by WFP even before fighting began.

The army has for days talked of an imminent assault on rebel-held Bor, the capital of restive Jonglei state, which has already swapped hands three times since fighting began.