Angelina Teny, the wife of South Sudan’s prominent opposition leader Riek Machar said a "fully fledged" genocide is underway in the country, where tens of thousands are facing hunger.

Teny, who is now in Australia, told Lateline on Tuesday that she is lobbying the Australian government and the South Sudanese community to step up aid.

She expressed concern over the Australian government’s decision cutting foreign assistance in its budget last week, while calling on Australia not to stop humanitarian aid.

"They are dying of starvation. Once famine is declared it means people have already died," she said.

The wife of the exiled rebel leader called on the divided South Sudanese community in Australia to reconcile. “You know the ruptured fabric of society at home actually spills over to the diaspora," she said.

"The diaspora actually contributes sometimes very negatively in that they use the social media and they have become what we as a party term 'internet warriors',” she added.

"We are telling them, turn your sharp pens into sending out good, positive messages, no matter which side you are on."