The Department of Foreign Affairs has confirmed that a number of Australians remain in South Sudan as United Nations chief Ban Ki-moon warns South Sudan over reports of crimes against humanity.
The city of Bor is in one of the most violent areas of the week-long conflict in which more than 1000 people are thought to have been killed.
Witness accounts are emerging of house-to-house killings and massacres.
The fighting is said to be between troops loyal to President Salva Kiir, and those loyal to his rival Riek Machar, a former vice president who was sacked in July.
Dor, a 24-year-old South-Sudanese refugee, says he knows of over a hundred Australian South Sudanese who are trapped in the country including his mother and brother.
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However it was too late for his uncle, who was killed on Sunday.
"My uncle was a survivor of war who lost his leg in the previous war, but he was not able to run away from such killings so he was shot right in the head," he told SBS.
He says the Australian government has not done enough to aid in evacuating them.
"If you look at the United Nation and the United Kingdom they went there to Juba and actually tried by all means possibel to get out their citizens, why can't Australia do that?"
DFAT has recommended all Australians leave immediately.
UN chief warns South Sudan over alleged war crimes
The official toll is 500 dead, although the real figure is believed to be far higher, aid workers say. Hundreds of thousands of others have fled to the countryside, prompting warnings of an imminent humanitarian disaster.
Rebel fighters are also reported to have committed atrocities in areas they control, as the oil-rich but impoverished nation, which won independence from Sudan to much fanfare just two years ago, appeared to be slipping deeper into civil war.
"Let me be absolutely clear. The world is watching all sides in South Sudan," Ban told reporters ahead of emergency Security Council talks on the crisis.
"The United Nations will 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."
Ban recommended the Security Council send 5,500 more soldiers to reinforce the UN's current 7,000-troop mission in the country, a move diplomats said was likely to be approved in a vote on Tuesday.
