Pressure mounts on South Sudan to end war

Regional nations have heaped pressure on South Sudan's warring parties to reach a ceasefire to end weeks of bitter fighting and atrocities on both sides that have devastated the young nation.

Thousands have been killed and half a million civilians have been forced to flee the fighting between troops loyal to President Salva Kiir and rebels allied to his sacked deputy Riek Machar.

Deadlocked ceasefire talks in Ethiopia are being mediated by the East African regional bloc IGAD, aimed to broker an end to a conflict about which the United Nations reports atrocities including mass killings, sexual violence and widespread destruction.

Fighting has spiralled into ethnic killings between members of Kiir's Dinka people - the country's largest group - and Machar's Nuer. Many fear conflict on the ground has spiralled out of the control of the politicians who sparked it.

Leaders of IGAD, the Intergovernmental Authority on Development, are due to hold a one-day summit in Juba on Thursday, South Sudan's foreign ministry spokesman Mayen Makol said.

The summit follows a visit on Monday by African Union Commission chief Nkozasana Dlamini-Zuma, who demanded both sides end the "senseless killings ... and end the humanitarian tragedy unfolding in their country".

A draft IGAD ceasefire accord, seen by AFP and presented to peace delegates meeting in Addis Ababa, notes the "scale of human suffering ... with great loss of human life, destruction of property and massive displacement" since fighting broke out on December 15.

The proposal demands an end to "all military actions", but also specifically highlights that both sides must "refrain from attacks on the civilian population", including summary executions, use of child soldiers as well as "rape, sexual abuse and torture".

Both sides would have to "freeze their forces" in their positions and create aid corridors, as agencies warn of a mounting humanitarian crisis.