As fighting persisted in parts of South Sudan's oil-producing region, Kenyan President Uhuru Kenyatta and Ethiopian Prime Minister Hailemariam Desalegn had "a constructive dialogue" with South Sudanese President Salva Kiir, according to Kiir's foreign minister. But the fugitive former deputy president who now leads renegade troops was not represented, and no political breakthrough emerged.
The next round of meetings will be held in the Kenyan capital of Nairobi, where regional leaders under a bloc known as IGAD are to meet Friday to discuss a report from Thursday's meeting, South Sudanese Foreign Minister Barnaba Marial Benjamin said.
Kiir agreed "in principle" to stop hostilities and to negotiate with former Vice President Riek Machar, who is expected to be formally invited by IGAD to attend upcoming peace talks, said Benjamin, who offered no details.
It was not possible to reach Machar, as his known phone numbers were switched off.
Government troops are trying to retake control of Bentiu, the capital of Unity state, from forces loyal to Machar. Fighting was also reported in Malakal, capital of Upper Nile state. Upper Nile and Unity comprise the country's key oil-producing region, raising concerns that unrest there could cut off the economic lifeblood of the young nation, which gets nearly its entire government budget from oil.
Citing more progress against rebels on the battlefield, South Sudan's minister of information told reporters that national forces on Thursday regained "full control" of Malakal. Michael Makuei Lueth said "criminal elements" had been looting the town, but the army now had it under control.
Military spokesman Col. Philip Aguer said government troops were "preparing to retake Bentiu as soon as possible."
The fighting has provoked fears of a civil war in the country that peacefully broke away from Sudan in 2011 following a 2005 peace deal.
The United States, Norway and Ethiopia are leading efforts to open peace talks between Kiir and his political rivals. Kiir said in a Christmas address that he is willing to "dialogue" with all his opponents.
The United Nations is investigating reports of mass killings since violence began spreading after a Dec. 15 fight among the presidential guards that pitted soldiers from Kiir's Dinka ethnic group against those from the Nuer ethnic group of Machar.
South Sudan's top U.N. humanitarian official, Toby Lanzer, said Monday that he believes the death toll has surpassed 1,000.
Although the capital, Juba, is now calm, fighting appears to be expanding, stretching the limits of humanitarian workers and aid agencies. The U.N. humanitarian office said aid agencies need $166 million to save lives amid the continuing violence.
The money will be used to provide water, sanitation, shelter, food and health care, plus protection for vulnerable people, the office said in a statement.
Some 58,000 people have taken refuge in and around U.N. bases in South Sudan, and more than 92,000 have fled their homes as a result of fighting, according to the U.N.
The U.N. Security Council last week voted unanimously to beef up its peacekeeping force in South Sudan. It called for an immediate end to hostilities and the "opening of a dialogue."
Hilde Johnson, head of the U.N. mission in South Sudan, said she expects some military reinforcements and equipment to arrive in 48 hours to help protect civilians seeking refuge at U.N. bases.
Before the 2005 peace agreement, the region that is now South Sudan fought decades of war with Sudan. One of the world's least developed countries, it still has pockets of rebel resistance and sees cyclical, tribal clashes that result in hundreds of deaths.
Muhumuza reported from Kampala, Uganda.
Associated Press writer Cara Anna at the United Nations contributed to this report.