U.S. Secretary of State John Kerry has warned of sanctions and other possible "consequences" if South Sudan's government and rebel forces do not commit to talks aimed at ending nearly five months of civil war.
Kerry, who spoke in the Angolan capital of Luanda Monday on the final leg of his African tour, had last week secured a commitment to talks from South Sudanese President Salva Kiir.
Kerry said rebel leader Riek Machar has a "fundamental decision" to make in the way he proceeds, adding that there will be accountability and implications for those who block these efforts.
VOA reporter Scott Stearns, travelling with Kerry, says Machar is now backtracking after initially seeming open to the talks in a telephone call with the secretary of state.
"Since that telephone call, Mr. Machar has told reporters that he sees no point in a meeting, or having any talks, about a transitional government that he believes could not be possible before a new election."
Kerry says despite Machar's recent comments, he believes the rebel leader has not rejected the talks outright.
The South Sudanese army battled Machar's rebels in the key oil town of Bentiu on Monday. The town fell into rebel hands last month.
The United Nations says a stray bullet from the fighting in Bentiu hit and killed a four-year-old child at the U.N. base in the town. More than 20,000 civilians are being protected at the base.
The United Nations has accused rebels of killing hundreds of people in Bentiu, based on their nationality or ethnic origin. The rebels have denied carrying out the killings.
A U.N. spokesman says there has also been fighting in recent days in Nasir, in the Upper Nile region, and a skirmish in the capital, Juba, between supporters of both sides, which U.N. troops broke up with tear gas.
The rebels and government signed a cease-fire agreement in January but fighting has continued.
Months of violence across several South Sudanese towns has led to thousands of deaths and driven more than 1.1 million people from their homes. Tens of thousands are sheltering in U.N. bases throughout the country.