Aussie warns on South Sudan violence

An Australian aid worker in the troubled new African nation of South Sudan is warning the brutal tribal violence sweeping the country is set to worsen.

Up to 25,000 women and children have fled into the bush as fighting between rival ethnic groups intensified in recent days, leaving dozens dead and threatening to destabilise the already fragile six-month-old African country.

The latest flare-up follows months of clashes that have killed hundreds since South Sudan finally declared independence from Sudan in July.

Save the Children's Melinda Young says the scale and viciousness of the most recent violence has been shocking.

"The level of brutality in this fighting is far above anything we've seen before," the Sydney woman told AAP from the South Sudanese capital Juba on Wednesday.

And given the South Sudanese government's limited capacity to address the violence, it is set to worsen further.

"The wet season we just came out of has been one of the most violent wet seasons we've had," Ms Young said.

"So now we're coming into the dry when more people can move about, so we would expect over the dry season the violence will escalate even more."

Ms Young said the fledging nation was facing a slew of other humanitarian emergencies, including an influx of refugees along the Sudanese border and violence waged by rebel militia groups hostile to the government.

She said international interest in South Sudan has waned since independence day and urged the world to re-focus on its potentially crippling emergencies.

Two Save the Children staff members in the town of Pibor were among those forced to flee the recent fighting.

"Neither of them have emerged yet. They've gone bush with their families," Ms Young said.

"We're quite concerned for their safety."

The Department of Foreign Affairs and Trade (DFAT) warns Australians not to visit South Sudan.

"We advise Australians not to travel to South Sudan due to the extremely dangerous security situation, the risk of armed conflict, the high level of violent crime and the high threat of terrorist attack," DFAT's travel advice reads.