Juba, South Sudan - In the suburb of Munuki in South Sudan's capital, men are digging fresh graves against a backdrop of large birds swooping through clouds of smoke billowing from an area where the new nation's rebel-movement-turned-army has its main barracks.



It was here that, a week ago, forces loyal to the President Salva Kiir, who hails from the country's largest Dinka tribe, battled breakaway forces loyal to his former deputy Riek Machar, who is from the second largest Nuer group. But the fight involving tanks and mortars between the two groups has tapped into an ethnic bitterness that has since swallowed up large chunks of a country whose identity was forged from decades of bloodshed fighting against Sudan.

Now, armed soldiers and apparently civilians with knives sticking from pockets and machete handles poking from football shirts roam a neighbourhood where the crackle of gunfire starts at 6pm - the government's new curfew - and where people vanish.



"The soldiers come at night and the guns go ko-ko-ko," said one of the last remaining residents, Moses, who was wearing a T-shirt emblazoned with the flag that was raised just two and half years ago, when South Sudan became the world's newest country.

After people are being killed, some of them are being thrown into the Nile, some of them are collected and they dig a big hole, and some of them are burnt. - Riek, a Nuer who says he recently defected from the presidential guard after overseeing some of the killings



Atrocities coming back

But some of the atrocities that killed an estimated 2 million people in the South during almost five decades of civil war are coming back to roost.



"After people are being killed, some of them are being thrown into the Nile, some of them are collected and they dig a big hole, and some of them are burnt", says Riek, a Nuer who says he recently defected from the presidential guard after overseeing some of the killings.



A few hundred metres from the smokestack lies a sign saying "Welcome to Eden City" and next to that, a freshly burnt corpse; scorched into the red earth. People say that it was left, just next to a church, as a message. Overnight it had been torched, probably as the stench had become unbearable to the few people left in this largely abandoned neighbourhood - where the abundance of scattered shoes and upturned chairs reflect a population yet again in flight.



"Everybody's running," said another resident Rose, "because of this one; war."

Further along the potholed track, a figure in military fatigues lies in a fetal position, but with his hands bound behind his back. The door-to-door killings here are carried out execution style after a simple language test - if the Nuer tribal scarification of deep horizontal lines carved into the forehead of men does not already make you an instant target.

'This is a tribal war'

"When they know you're Nuer, they don't have any more questions. It's just a bullet to your head," said a student, Jickson, who fled the house he was staying at after seeing several friends killed.



"They tied their hands behind them and they slaughtered them," he said, drawing a line with his finger across his throat, his mouth shaking at the memory.



Now, he doesn't know where to run. "This is not a political war. This is a tribal war," he said.

The region's legacy of protracted warfare - where allegiances shifted and communities were pitted against one another for years - is evident in inter-communal clashes that kill thousands every year, as age-old cattle-raiding has been exacerbated by modern weapons.



In Jonglei state, militias of up to 10,000 men and boys have tried to slaughter one another, while the government has denied such killings. Meanwhile, abuses against minority tribes and the potential for more has become contagious. The political feud has pushed ethnic tensions to the verge of a new civil war, while authorities are keen to couch this as merely the fallout of a failed coup.



Army spokesperson Malaak Ayuen Ajok said that any killings carried out had been committed by "criminal elements" and not government forces.



Massacres reported

Just down the road from the barracks in Juba, around 10,000 other people - mainly Nuer - are sheltering at a UN base, some of the over 50,000 at UN bases nationwide. Some like Simon, who is nursing four gunshot wounds, carry chilling tales of massacres by security forces who, he says, rounded up him and 250 other men.



"They talked to us in Dinka language and if you couldn't speak back, they knew you were Nuer and took you to the police building," he said. Simon said that they all were locked inside the police building.





"After that, they shot us for two days, morning and evening, through the windows," he said.



"They'll put people in trucks and you'll never see them again," said Bang Teny, who only returned to South Sudan from Canada in March to help build the nation and is now desperate to get out.



"The gunfire you can hear at night. It's people being taken outside and shot," said one aid worker who asked not to be identified. "The reason for the curfew is that they transport bodies around."



"Most of the time they collect them at night with big lorries," said Riek, adding that he knew "they were being collected" at the barracks.



The UN estimates that at least 1,000 people have been killed in the conflict, which is not just isolated to Juba. Nor are the reprisal killings only seen in Jonglei, the Upper Nile and Unity state. According to witness testimony, it is much more widespread and affecting even the smallest tribes.



"The numbers they are saying are completely wrong. People are being killed everywhere," Riek added, estimating that the figures do not even cover one suburb in Juba.



Mass graves found

On Thursday the UN's top Human Rights chief Navi Pillay alerted the world to at least two mass graves in Juba and one in Bentiu, the capital of Unity state, where a largely Nuer army and militias have also gone on the rampage.



At Juba airport, hundreds of foreign oil company workers were lining up to leave on Sunday after battles over the oil fields that a technician, Hassan Ali, said were between South Sudanese fighters.



"They were using stones and knives," he said, making motions of heads being stoved in, while his colleagues talked about men's hands being cut off before execution.





Back in the capital's eerily silent neighbourhoods, destroyed documents litter the ground outside homes that some fled, leaving half eaten meals.



"We think it's to make sure that no one knows who's missing, or how many" said one aid worker, whose main question was: "Where are the bodies?"



In other areas, the attacks are more crude. A tank moved slowly amid the sound of gunfire near where Yien and his brother's family were hiding at home in the Jabarona suburb. When the tank burst through the wall, it crushed Yien's one-year-old niece, his sister-in-law and another 6-year-old relative.



"The tanks came and ran over the house. We men escaped but the woman and children were killed...We didn't hear it coming," said Yien, who managed to leap out of the front door with his brother.



He said that the killings were targeted, as his home was flanked by neighbours from different ethnic groups whose homes were untouched.



"I believe there was someone in the tank showing people where the Nuer lived, as it was not every house."



In the neighbourhood of Mangaten, people were piling up belongings on carts from shops and homes that have had windows and doors ripped wide open, while a few of their neighbour's square tin shacks remain untouched and neatly locked up.



"They know all our houses, the Nuer who are near to them, they know them all, especially those who came and killed my two cousins, they were my neighbours," says Cornelius, who broke through his fence to flee the presidential guard when they came to his house after he began hearing the pop of gunfire at five minute intervals.



"We didn't know that it was going to be an issue with civilians, we thought it was a military problem," he said.



But like hundreds of thousands of other South Sudanese, Cornelius is now faced with a familiar dilemma of fight or flight.