Heavy gunfire has been heard in South Sudan's capital, as mediators announced that direct meetings between the nation's warring sides had begun.
Explosions from reported artillery shells and the rattle of automatic gunfire were heard on Saturday night in Juba's key government district, where most ministries, the presidential palace and the parliament are located, the AFP news agency reported.
The violence came as Ethiopian government announced the latest attempt had started to strike a ceasefire deal to end nearly three weeks of conflict. The announcement was contrary to reports earlier in the day that they had been delayed.
"We wish all our best for the successful conclusion of the direct peace talks of South Sudan which is being officially opened," said the Ethiopian foreign minister, Tedros Adhanom, as the two sides met at a ceremony in the Ethiopian
capital Addis Ababa.
"South Sudan deserves peace and development not war. We appreciate the members of the two negotiating teams for the progress they have made today."
Dina Mufti, an Ethiopian foreign ministry spokesman, said full talks about a proposed ceasefire would begin at 1200 GMT on Sunday.
"Both the government and opposition of South Sudan have committed to resolve their political differences through political dialogue," said Seyoum Mesfin, a former Ethiopian foreign minister and the special envoy for IGAD, the East African regional bloc of nations that is mediating the talks.
Since the conflict erupted on December 15, thousands of people are feared to have been killed in the fighting, pitting army units loyal to President Salva Kiir against a loose alliance of ethnic militia forces and mutinous army
commanders nominally headed by his rival, former vice president Riek Machar.
In South Sudan on Saturday the army battled to wrest back from rebels the strategic town of Bor, capital of Jonglei, one of the country's largest states.
There were reports of intense battles involving tanks and artillery on the outskirts of Bor, which has already exchanged hands three times since fighting began almost three weeks ago.
IGAD, the Inter-Governmental Authority on Development, whose members include the talks host Ethiopia as well as Kenya and Uganda - all strong backers of Kiir's government - played key roles in pushing forward the 2005 deal that ended Sudan's two-decade-long civil war.
Uganda has deployed troops inside South Sudan to evacuate its citizens and bolster support for Kiir.