South Sudanese rebels and the government are scheduled to sign an agreement that could end weeks of deadly violence.
The East African regional bloc IGAD says there will be a signing ceremony Thursday for what it calls "an agreement on cessation of hostilities".
It says the sides will also sign an agreement on the issue of political detainees held by the South Sudan government.
IGAD has spent weeks holding talks in Ethiopia with representatives of South Sudan's President Salva Kiir and anti-government forces.
There was no initial word on the terms of the agreement. Earlier, talks had bogged down over the government's refusal to release political detainees.
South Sudan's crisis was touched off by a December gun battle at army headquarters in the capital, Juba. President Kiir accused former vice president Riek Machar of attempting a coup, a charge Machar denied.
Earlier this week, a U.N. human rights official said "thousands" of people had been killed since the South Sudan conflict broke out in mid-December.
The U.N. Office for the Coordination of Humanitarian Affairs (OCHA) said in its most recent report that 494,000 people are internally displaced in South Sudan and 86,100 have fled to neighboring countries.
No precise death toll has been established, but a top U.N. official said this week after a visit to the country that "many thousands" were likely to have been killed
More than 70,000 civilians have sought shelter on eight U.N. bases in South Sudan since clashes erupted in mid-December between pro- and anti-government forces.
Around 22,000 civilians are sheltering at the U.N. base in Malakal, the capital of oil-producing Upper Nile state.