Government troops and SPLM/A in Opposition forces clashed on Friday in heavy fighting in Bentiu, Unity State.
Media agencies reported that the fighting continued for several hours around the key airport zone outside the town, close to a United Nations Mission in South Sudan or UNMISS base.
The reports added that government already lost contact with its ground forces in Bentiu.
Acting SPLA Spokesman Joseph Mariel Samuel accused Opposition forces of launching a dawn attack in Ayod of Jonglei State saying they were repulsed with heavy casualties.
Opposition spokesman Brigadier Lul Ruai Koang said the violence was the start of a “long-awaited government offensive’, claiming that their forces seem to be in control of Bentiu.
The renewed fighting came just three days after UN envoys visited the country and warned the government and the Opposition of “consequences” if fighting continues.