South Sudan's rebel chief Riek Machar has agreed to attend direct talks with President Salva Kiir to end a four-month long civil war, UN Secretary-General Ban Ki-moon has said.
Ban, who landed in war-torn South Sudan on Tuesday, told reporters that Machar promised he "will be present" at talks in the Ethiopian capital.
Ban's comments, reported by AFP news agency, came moments after he spoke to the rebel chief via satellite telephone in his remote bush hideout.
Kiir has already promised to attend talks with his arch rival.
Tuesday's visit, which comes as rebels and government forces battle for control of a key oil town, is the latest major push for a ceasefire in the conflict that has seen the world's youngest nation collapse amid a brutal cycle of war crimes.
Both sides in the conflict have been accused of widespread ethnic massacres, rape and the recruitment of thousands of child soldiers.
Al Jazeera's Anna Cavell, reporting from Juba, said that Ban's first priority during his one-day visit was the protection of civilians living in UN bases.
With about 80,000 people taking shelter in UN bases across the country, including 20,000 in the capital, "people have considered this to be a great success for the UN as it fulfills its mandate to protect civilians," Cavell said.
"But now, what we have is a potential long-term problem for the UN as these bases are not sanitary, and a lot of them are not fit for humans to live in.
"Also, very recently in the town of Bor, we saw civilians sheltering in a base come under attack from the outside despite the presence of UN peacekeepers," Cavell said.
Many of the occupants are too frightened of attacks to leave the protection of the peacekeepers.
Ban's arrival comes days after US Secretary of State John Kerry visited the country and extracted promises from Kiir to meet face-to-face with Machar, a former vice-president who leads the rebel forces.
But despite warnings of US sanctions if fighting continued, the government has pushed forward with a major offensive to claw back towns from the rebels, capturing one of their strongholds and forcing Machar to flee into the bush.
Ban last visited South Sudan amid euphoric celebrations at its independence from Sudan in July 2011, after it voted to split away following decades of war with Khartoum.