Khartoum, Sudan (CNN) -- More than 100 people were killed and scores of others injured in clashes between the Southern Sudan government and forces loyal to a militia leader last week, a Southern Sudan official said.
Forces loyal to George Athor "attacked the town of Fanjak," said Peter Aguer, spokesman for the Sudan People's Liberation Army movement. Twenty SPLA soldiers, 39 civilians and 30 of the attackers were killed, he said.
In addition, Athor's forces also attacked the town of Bor, where four SPLA soldiers and 12 attackers died -- a total of 105 dead, Aguer said.
The clashes took place Wednesday and Thursday.
The SPLA is the military wing of the Sudanese Liberation Movement that governs Southern Sudan. In results of a referendum announced earlier this month, the south voted to split from Sudan and create a new nation.
Athor took up arms in 2010 when he was not elected governor of the Southern Sudanese state of Jongeli. He accused the Southern Sudan government of election fraud, but signed a truce in January, days before the referendum.
"We support the memorandum we made with him and we will communicate to reach a peaceful resolution," said Yein Mathew, spokesperson for the SPLM.
As the nation readies for official independence on July 9, violence caused by renegade militias has been a concern. Last week, a mutiny among the Joint Integrated Units (JIUs) led by soldiers loyal to militia leader Gabriel Tang resulted in up to 50 deaths. Sixty-five civilians were also injured.
The JIUs are a coordinated military force consisting of the northern Sudanese Armed Forces (SAF) and the southern Sudanese Peoples Liberation Army. Tang's forces had been merged into the units along with SAF.
Doctors Without Borders said in a statement it was "currently responding to a large influx of wounded patients as a result of clashes that began ... in Upper Nile State, Southern Sudan."
"We are mainly seeing patients with gunshot wounds, and many have significant abdominal and limb injuries," said Tim Baerwaldt, head of mission for Doctors Without Borders in Southern Sudan.