South Sudan's government forces have overtaken the rebel-held stronghold and opposition headquarters of Pagak, along the Ethiopian border, William Gatjiath Deng, spokesman for the opposition IO, told The Associated Press.
"They took the main town and our forces are now regrouping," said Deng.
Army spokesman Lul Ruai Koang did not confirm the reports saying that he's "not aware" of Pagak's takeover.
The rebels burned their military barracks before fleeing, to prevent government forces from being able to use the ammunition, according to residents.
"While this is a significant symbolic setback for the IO it remains to be seen whether the government can secure the position so deep in IO territory," said an aid worker familiar with the situation in Pagak, who insisted on anonymity for security reasons.
Earlier this year the government declared a unilateral ceasefire, however there have been continued reports of government-led offensives into Maiwut and toward Pagak, including killings of civilians and burnings of houses.
In July, the United Nations reported that 25 aid workers were evacuated from Pagak due to attacks.
Since South Sudan spiraled into civil war almost four years ago, Pagak has been the headquarters of the opposition rebels, led by former Vice President Riek Machar, who is in exile in South Africa. The IO rebels still hold territory in Panyijar Country in Unity state as well rural areas of Jonglei state and Akobo state, traditionally areas where South Sudan's Nuer people live.