Clashes broke out in the capital Juba just over a week ago after President Salva Kiir accused his former deputy Riek Machar of an attempted coup.
The fighting has spread to other parts of the country with many towns falling into rebel control.
The Department of Foreign Affairs and Trade has confirmed there are a number of Australians still in South Sudan.
David Chiengkou from SBS Radio's Dinka program and currently in Kenya's capital Nairobi, says he's been communicating with Australians still in South Sudan.
He says he is particularly concerned about the safety of Australians in the town of Bor in Jonglei state.
"One of my friends as well, who is an Australian citizen who travelled with his wife and three boys. He lives in Melbourne, from Narre Warren. Now he got himself locked in Bor and I have no communication with him," Mr Chiengkou said.
"Whether he's able to cross over to the other side of the river. So I'm still tracking them. A lot of Australian citizens are locked into Bor and there are no evacuation policies that are there to help them."
Listen: David Chiengkou interviewed by Santilla Chingaipe
