United Nations in uproar after the highest number of Aid worker killed in one incident

United Nations is in uproar after six aid workers were killed in an ambush in famine-hit South Sudan on Saturday.

UN reported about the alarming incident on Sunday, without specifying what organisation the humanitarian workers were worked for.

The victims were attacked on Saturday as they travelled from the capital, Juba, to the eastern town of Pibor, according to the UN Office for the Coordination of Humanitarian Affairs (OCHA).

"I am appalled and outraged by the heinous murder of six courageous humanitarians in South Sudan," Eugene Owusu, the UN humanitarian coordinator for South Sudan, said in a statement.

"At a time when humanitarian needs have reached unprecedented levels, it is entirely unacceptable that those who are trying to help are being attacked and killed," Owusu added.

According to OCHA, it was the highest number of humanitarian workers killed in one incident since the start of a civil war more than three years ago.

Some 100,000 people are suffering from the man-made famine in South Sudan and another million are not far off after a nasty stop-start three-year civil war in which starvation has become a battlefield tactic.

It is no coincidence that areas afflicted by famine are opposition areas, home to mostly ethnic Nuer and controlled for the most part by rebels, a leaked report by United Nations investigators said last week.