The chief negotiators for South Sudan's government and rebels held another face-to-face meeting on Sunday in preparation for the start of formal ceasefire talks between the two sides, officials said.
A spokesman for the rebel team said their delegation leader, Taban Deng, met in the Ethiopian capital with Nhial Deng Nhial, head of the government negotiation team.
A South Sudanese government spokesman said an agenda for the talks had now been approved, but that it was still unclear when the negotiations would begin in earnest.
"The leaders of both delegations met today. We are waiting for a briefing. Nothing is happening now," rebel team spokesman Yohanis Musa Pouk said.
South Sudan Information Minister Michael Makuei said the two sides were no waiting for IGAD -- the East African regional grouping that is brokering the talks -- to present a plan for the negotiations.
"We have approved the agenda and we are waiting for IGAD to give us the official programme," he said.
After days of corridor diplomacy, Ethiopian officials had said they expected the negotiations on a ceasefire to get under way on Sunday. But they appear to have been bogged down in what one diplomat described as "protocol issues".
The diplomatic effort is aimed at ending three weeks of fierce fighting in the world's youngest nation that has left thousands dead and close to 200,000 people displaced.
A key sticking point appears to be rebel and international demands that the South Sudanese government release 11 officials close to rebel leader Riek Machar, a former vice president who President Salva Kiir accuses of starting the violence by attempting a coup on 15 December.
The South Sudanese government repeated earlier Sunday that the rebel suspects would not be freed and should face justice.
In addition, both sides have continued to be locked in fierce fighting across the country.