Juba (AFP) - Heavy fighting broke out Wednesday in South Sudan's war-ravaged northeastern town of Malakal, pitting rival factions of government troops against each other, the army and aid workers said.
The town had already been left in ruins last year after repeatedly swapping hands between rebels and the government.
The latest clashes in the capital of the oil-producing Upper Nile state pitted troops loyal to the state governor against those of rogue general Johnson Olony, an ex-rebel who commands a pro-government ethnic Shilluk militia.
Last month, Olony was ordered to report to army headquarters after the United Nations reported he had abducted many child soldiers, perhaps as many as hundreds.
In Malakal, powerful explosions could be heard shortly after dawn, said an aid worker in the town who asked not to be named.
Army spokesman Philip Aguer said two soldiers had been killed in the fighting that first broke out late on Tuesday due to a "misunderstanding", and again on Wednesday morning. Shooting calmed later in the afternoon.
Aguer said rumours Olony had defected to rebels were "cheap propaganda."
Residents of Malakal told independent Radio Tamazuj they could hear "gunfire from all sides".
The violence is the latest round in South Sudan's civil war, which erupted in December 2013 when President Salva Kiir accused Riek Machar, who had been sacked as vice president, of attempting a coup.
The war that is devastating the world's youngest nation has killed tens of thousands of people, and left over half of the country's 12 million people in need of aid, according to the United Nations.
- Attacks on aid workers -
The UN World Food Programme (WFP) meanwhile said it was suspending food aid deliveries to parts of Upper Nile state, scene of some of the heaviest recent fighting, as it was too dangerous to send its staff in.
At least 10 aid workers have been confirmed killed in the state since civil war broke out 16 months ago, according to the UN.
"We cannot do our life saving work unless national and local authorities are willing and able to safeguard humanitarian staff," WFP said in a statement, announcing the suspension of aid to Upper Nile's Akoka and Fashoda counties.
Three WFP workers disappeared on April 1 when they were caught up in fighting as they drove a food aid convoy, while a fourth was abducted at gunpoint from Malakal in October 2014.
"Worsening insecurity in some parts of South Sudan will make it harder for humanitarian agencies to reach conflict-affected communities with badly needed assistance, just as the lean season is set to begin," WFP added.
"We are equally concerned about the welfare of innocent people, particularly women and children, who are suffering the consequences of this conflict," it said.
Peace talks in Ethiopia's capital Addis Ababa collapsed in March and the impact of more than 16 months of war continues to grow.
Well over 117,000 civilians are sheltering in UN bases across the country.
At least 1,500 more have arrived in the camp at Malakal since the latest fighting started, the UN says.
International charity Oxfam this week warned that "skyrocketing inflation, conflict and collapsed markets are pushing people in South Sudan to breaking point".
South Sudan's currency, the pound, now trades at half its official value on the black market, Oxfam said.
Food prices in key battleground northern and eastern states of Jonglei, Upper Nile and Unity have soared by 300 percent, according to the UN.
Children have suffered terribly as a result of the war, with government and rebel troops forcing some 12,000 minors to fight in their ranks, the UN children's agency says.