South Sudan's warring parties opened negotiations in Addis Ababa Saturday to strike a ceasefire deal and end nearly three weeks of conflict, Ethiopia's foreign ministry said. "We wish all our best for the successful conclusion of the direct peace talks of South Sudan which is being officially opened," said Ethiopian Foreign Minister Tedros Adhanom, as the two sides met at a ceremony in the Ethiopian capital. "South Sudan deserves peace and development not war. We appreciate the members of the two negotiating teams for the progress they have made today." Ethiopian foreign ministry spokesman Dina Mufti said full face-to-face talks 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 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.