The aid group Doctors Without Borders says violence in a volatile South Sudanese state has led to "an unprecedented humanitarian crisis" there.

The group said Friday that its teams in the state of Unity are getting daily reports of extortions, abductions, mass rapes and killings, and have witnessed villages burned to the ground and crops looted and destroyed.

It said in a statement that as the conflict intensifies despite the signing of a peace deal in August, civilians are being subjected to "a level of violence and brutality" not seen before.

Unity is one of two states witnessing fighting as government troops and rebels battle for control.

The violence has forced the population to flee their homes repeatedly and to hide for long periods in the bush.