Delegates for South Sudan's government said they are prepared to sign a cease-fire "soon," as negotiations continue with anti-government fighters on a proposal to end weeks of deadly violence.
Both sides made statements Wednesday in Ethiopia's capital, a day after regional mediators presented a draft peace agreement.
The rebels did not specify that pro-rebel officials held by the government must be released as part of a deal, but said their detention remains an obstacle.
The government has said it can release them only after "legal procedures" are carried out.
The violence in South Sudan has killed more than 1,000 people and forced about 200,000 from their homes.
In a Tuesday briefing, U.N. deputy spokesman Farhan Haq said there are reports of continued fighting near the rebel-held town of Bor, capital of Jonglei state.
Haq said U.N. peacekeepers reported seeing villages burned and looted in Unity state, and local officials report severe food and water shortages.
South Sudan's unrest began December 15 when renegade soldiers attacked an army headquarters. President Salva Kiir accused former vice president Riek Machar of a coup attempt. Machar had called for the army to overthrow the president.
Witnesses saidsome of the violence is ethnically motivated, with supporters of Kiir, a member of the Dinka tribe, and supporters of Machar, from the Nuer tribe, targeting each other.
The U.N. refugee agency (UNHCR) said it is struggling to keep up with the humanitarian needs of the thousands of South Sudanese refugees who have crossed into Uganda to escape violence. The agency said refugees are now crossing into Uganda at a rate of up to 2,500 a day.
The agency also said a growing number of refugees are also making their way into Ethiopia and Kenya.