JUBA, South Sudan (AFP) - The UN humanitarian chief in South Sudan warned on Sunday, Dec 23, 2013, that the country has "unravelled" after a week of violence that has transformed a power struggle within the ruling party into a quasi-civil war.
The world's youngest nation, which gained independence from Sudan in 2011 after decades of combat, is falling apart under the pressure of rebel groups seizing towns and oil fields and militias from the country's two largest tribes massacring one another after a fall-out between the President Salva Kiir and his former deputy Riek Machar.
"It would have been have been difficult one week ago to imagine that things would have unravelled to this extent," said Mr Toby Lanzer, South Sudan humanitarian coordinator for the the United Nations and deputy head of its peacekeeping mission UNMISS.
"As we go to bed tonight, there are hundreds of thousands of South Sudanese who've fled into the bush or back to their villages to get out of harm's way," he said.
Asked which areas of the conflict-torn country he was concerned about, after a week of attacks even on UN bases and reports of mass killings, Mr Lanzer said: "It would be quicker to talk about which areas I'm not worried about."
He said the current crisis, which has forced the evacuation of almost all expatriates, was the result of "an armed struggle within the ruling party with innocents stuck in the middle". He feared things could drastically change again in a week's time.
Mr Lanzer said that he was particularly worried about Jonglei, a vast and already volatile state in the east of the country that has been the scene of particularly fierce fighting.
Rebels from the country's second-largest tribe, the Nuer, to which Mr Machar belongs, have seized control of Jonglei, fighting either under a defected general or as part of a sub-clan youth militia.
On Thursday, an attack by around 2,000 youths from the Lou Nuer sub-clan on a UN base in Akobo, in northern Jonglei, resulted in the deaths of two Indian peacekeepers and the wounding of a third, as well as the deaths of up to 20 civilians from the country's largest Dinka tribe that President Kiir belongs to.
Mr Lanzer had just returned from a trip to Jonglei's main city of Bor, where he said "a battle... looms" after various reports of groups mobilising.
The UN is "fortifying the camp in Bor, making sure there is no repeat of Akobo... But, as in Akobo, if there are few peacekeepers inside and 2,000 (fighters) outside, there's little we can do."
Mr Lanzer said he was also concerned about the security situation in South Sudan's two oil-producing states of Unity and Upper Nile and, increasingly, Lakes state.
In the main towns, Mr Lanzer said, the UN was better placed to offer protection and was doing its "level best". But it had "4,000 infantry to use across the country" - an area equivalent in size to Spain and Portugal together.
The potential to beef up numbers was thwarted by a separate ongoing crisis in Central African Republic that also threatened to spill over into civil war.
In the absence of more peacekeepers, Mr Lanzer's best advice for those in South Sudan was "to sit tight - it's probably the safest bet".
But even at the UN peacekeeping base in Juba, thousands of Nuer fleeing what they describe as targeted killings in the capital, said they were not safe, with men coming in with smuggled guns to pick off their rivals.
Meanwhile, the UN has evacuated "a considerable number of UN and NGO workers" from major sites such as Yida, home to 70,000 refugees from Sudan, and smaller bases, and is sending all non-essential staff out of the country.