'Mass ethnic killings' in South Sudan

New details are emerging of alleged ethnic killings committed during more than a week of violence in South Sudan.

A reporter in the capital Juba quoted witnesses as saying more than 200 people, mostly from the Nuer ethnic group, were shot by security forces.

Another man in Juba said gunmen from the majority Dinka ethnic group were shooting people in Nuer areas.

The violence comes amid a power struggle between President Salva Kiir, a Dinka, and his Nuer ex-deputy.

South Sudan's government has denied it is behind any ethnic violence.

The reports emerged as UN Secretary General Ban Ki-moon called on the Security Council to add 5,500 UN troops to the 7,000-strong force in South Sudan.

Rebels supporting sacked former vice-president Riek Machar have seized major towns over the past week.

Tens of thousands of people have fled the fighting.

'Eyewitness account'

The journalist in Juba, Hannah McNeish, told the BBC that she had interviewed a man called Simon, who was shot four times but managed to survive a mass killing.

"He tells of being rounded up with about 250 other men, driven to a police station in one of Juba's busiest suburbs. He describes an ordeal whereby over the course of two days, forces outside the windows fired into this room, killing all but 12 men."

McNeish said this account had been "corroborated by two other survivors who are all at the UN camp".

Another man interviewed at the UN base in Juba reported that gunmen from the Dinka tribe were shooting people in Nuer districts who did not speak the Dinka language.

Meanwhile, UN humanitarian co-ordinator Toby Lanzer, who was in Bor, north of Juba, over the weekend, told the BBC he had witnessed "some of the most horrible things that one can imagine".

The town of Bor is being held by the rebels.

The claims of atrocities have not been independently verified.

Up to 1,000 people are thought to have been killed in the fighting and UN compounds are sheltering more than 40,000 civilians.

'Face the consequences'

The conflict began last week, when President Salva Kiir accused Mr Machar, from the Nuer ethnic group, of attempting to launch a coup.

Mr Machar, who was sacked as vice-president in July, denies trying to seize power.

The fear is that their personal rivalry will spark a full-scale conflict between the Nuer and Dinka groups.

On Monday, Mr Ban urged the Security Council to strengthen the UN mission in the country, Unmiss, "on an urgent basis in order to help ensure the protection of civilians and the protection of United Nations personnel".

He requested that 5,500 troops be reassigned from UN missions in other African countries, including Liberia and Democratic Republic of Congo.

In addition, he asked for hundreds more police, three attack helicopters, three transport helicopters and one military transport plane.

Earlier he said would "investigate reports of grave human rights violations and crimes against humanity".

"Those responsible at the senior level will be held personally accountable and face the consequences, even if they claim they had no knowledge of the attacks," Mr Ban added.

Two Indian peacekeepers were killed last week in a rebel raid on a UN compound.

The fighting began in the capital Juba last week after Mr Kiir said he had quashed an attempted coup.

Since then, violence has spread throughout South Sudan, with rebels taking the major towns of Bor and Bentiu.

President Kiir told parliament earlier that he was willing to hold talks with Mr Machar, saying that a delegation of East African foreign ministers had offered to mediate.

However, he said that Mr Machar would have to come to the table without any conditions.

Mr Machar told Reuters news agency that he was open to dialogue if his political allies were released from detention.

Over the weekend, the US deployed extra troops to help evacuate Americans and other foreigners.

Sudan suffered a 22-year civil war that left more than one million people dead before the South became independent in 2011.

-BBC