UN chief makes strong push for peace on S. Sudan visit

South Sudan's warring sides have "no option" but to respect a peace deal, UN Secretary General Ban Ki-moon said Thursday as he visited the war-scorched nation.

Ban said the enduring "nightmare" in the world's youngest country included "killings, rapes, children forced to become soldiers," and "over two million people forced to flee their homes."

"The government of South Sudan must step up...(to) its responsibility and protect its population," he said after talks with President Salva Kiir and his estranged former deputy Riek Machar, whose dispute triggered civil war in December 2013.

UN Secretary General Ban Ki-moon (C) leaves the State House in Juba, after his meeting with South Sudan's President, on February 25, 2016, as part of his tour in Eastern Africa ©Albert Gonzalez Farran (AFP)

"South Sudan now has a peace agreement signed last August... (not) respecting the terms of the peace agreement is not an option, it is a must," Ban said.

Ban also said the UN would provide $21 million (19 million euros) in aid "to remove restrictions on the freedom of movement of the UN and humanitarian actors."

Fighting has continued despite the August peace deal.

At least 18 people were killed in the latest incident in the north-eastern town of Malakal last week when government soldiers participated in an attack on a UN-protected camp for nearly 50,000 civilians seeking shelter from the war.

The August agreement, signed under international pressure, leaves Kiir as president and returns Machar to his old job as deputy, but in a sign of the levels of mistrust between the two men Machar remains in exile despite his reappointment earlier this month.

- 'Peace above politics' -

Ban, who held talks with Machar over the telephone, said: "My message to the leaders of South Sudan is clear: put peace above politics, pursue compromise, overcome obstacles, establish (a) transitional government of national unity and do not delay it."

The battle for control of the country has repeatedly pushed South Sudan to the brink of famine, with millions only saved from starvation by the intervention of the UN and aid agencies.

South Sudan won its independence from Sudan in July 2011 after decades of civil war.

But less than 18 months later Kiir and Machar's political battle for control of the ruling Sudan People's Liberation Movement (SPLM) became a real war splitting the country along ethnic lines, pitting Kiir's Dinka people against Machar's Nuer.

The conflict has been marked by rights violations and attacks on civilians with children murdered or recruited into militias, women and girls abducted into rape camps and used as sex slaves, multiple ethnic massacres, attacks on UN bases and aid workers.

An African Union investigation published last year found evidence of forced cannibalism and concluded that war crimes had been committed.

A succession of UN rights reports have also found evidence of war crimes.

Neither Kiir nor Machar have faced any sanctions for the actions of armed forces under their command.

UN Secretary General Ban Ki-moon (L) shakes hands with South Sudan's President Salva Kiir, as he leaves the State House in Juba after their meeting, on February 25, 2016, as part of his tour in Eastern Africa ©Albert Gonzalez Farran (AFP)