The South Sudanese government and rebel forces have blamed each other for clashes erupted in the oil-rich town of Malakal on Tuesday (31 January). It is not yet clear how many soldiers and rebels died in the incident.
A government official told Reuters that Sudan People's Liberation Army (SPLA) soldiers had been provoked by rebels from the Sudan People's Liberation Movement-in-Opposition (SPLM-IO).
The official added the army had been instructed "not to wage offensives against the rebel forces" in line with President Salva Kiir's call to engage in a national dialogue to end the ongoing conflict.
However, rebel spokesman William Gatjiath Deng said government troops launched several attacks on rebel positions.
"In the fight this morning, Juba regime suffered heavy losses in human and material, as bodies of the Juba regime soldiers lie everywhere," he said.
The latest clashes erupted just one day after the United Nations warned the situation remained tense in Malakal, which it described as "largely deserted".
IBTimes UK's exclusive interview with Machar:
South Sudan descended into war in 2013 – just two years after gaining independence from Sudan – when Kiir, of the Dinka ethnic group, fired his deputy and rebel leader RiekMachar from his cabinet.
Ethnic-related violence targeting Dinka and Nuer ethnic groups then spread. An estimated 50,000 people have been killed, amid allegations of crimes against humanity committed by both sides, including rape, torture and the use of child soldiers. Millions are displaced and are facing severe food shortages due to a man-made famine.
Kiir and Machar have agreed on several peace deals – the last of which was signed in August 2015 – but have failed to control their troops, who have broken every ceasefire since 2014.
Machar, who leads the opposing faction Sudan People's Liberation Movement-in-Opposition (SPLM-IO), fled South Sudan following deadly fighting in Juba in July.