Government troops and rebel fighters engaged in a fierce battle over an important oil town Monday after rebels launched a counter-offensive shortly after the government claimed control of the town.
Bentiu has seen fierce battles over the last 24 hours, said the aid group CARE, which added that its staff is taking shelter in bunkers on the U.N. base. The rebels launched a counter-offensive Monday and the city may have changed hands yet again, according to a security expert, who insisted on anonymity because he is not authorized to speak to the press.
A government offensive on Sunday came just days after South Sudanese President Salva Kiir told U.S. Secretary of State John Kerry that he was ready to hold peace talks with the rebel leader, former Vice President Riek Machar. But a spokesman for Machar's negotiating team in Ethiopia told The Associated Press on Monday that Machar first wants a "program" that includes a timeline for the formation of a transitional government as well as its composition and structure.
"The Americans are pushing us to go to Juba and form an interim government. We cannot go there without an agreement on a program first. We need to know who will be in that transitional government, in what capacity, for how long and issues like that," said the spokesman, Yohanis Musa Pouk.
In a statement Monday, Kerry said the U.S. "condemns in the strongest terms recent offensives by South Sudanese government forces against opposition-held positions" and said they contradict Kiir's commitments in recent days. Kerry called on all sides to stop all offensives and said Kiir and Machar should "meet directly in the coming days to end the conflict."
In Ethiopia, meanwhile, South Sudan's government and rebel negotiators signed a document pledging to open safe-travel corridors for aid workers. The agreement also urged the sides to recommit to a discarded peace deal signed in January.
The regional political bloc known as IGAD urged the sides for a one-month peace period — from May 7 to June 7 — to allow crops to be planted and tended. The U.N. has warned of potential famine if crops aren't planted and harvested.
From South Sudan's government, Nhail Deng Nhail said the signing of the document is vital because of the approaching rainy season.
"We herein commit ourselves to facilitate humanitarian access to all parts of the country. However, we would have wished we signed today the entire agreement recommitting the parties to observe the whole cessation of hostilities agreement," he said.
On the rebel side, Gen. Taban Deng said the deal would help prevent hunger. Deng also accused South Sudan of intensifying attacks against rebel positions amid Kerry's peace efforts. Deng said the Juba government's prime agenda "is war, not peace."
South Sudan military spokeman Col. Philip Aguer said early Monday that government troops had captured Bentiu from rebels on Sunday. But there were indications later Monday that the rebels may have again won over the city, according to the security expert who insisted on anonymity.
South Sudan has been rocked by violence since December, when Kiir accused Machar of staging a coup. Thousands of people are believed to have been killed and 1 million people have fled their homes. The violence has taken on an ethnic dimension between Kiir's Dinka community and Machar's Nuer community.
Rebel fighters from the Nuer ethnic group took control of Bentiu in mid-April and slaughtered non-Nuer civilians in the town mosque, the hospital and on streets, leaving "piles and piles" of bodies behind. The U.N. Security Council expressed "horror" at the massacre.
Kiir fired the country's top military officer last month, Chief of Staff Gen. James Hoth Mai, further isolating the Nuer group politically. Mai is Nuer and his command position, which he held since 2009, was frequently cited as an example of the ethnic diversity of the government led by Kiir, an ethnic Dinka.
Machar has said he wants to see the exit of Kiir, whom he accuses of acting like a dictator.
South Sudan peacefully broke away from Sudan in 2011 after a decades-long fight for independence.
Jason Straziuso reported from Nairobi, Kenya. Tom Odula in Nairobi contributed to this report.