A former high-ranking southern army member who rebelled against the southern government following April elections broke a January cease-fire by attacking the towns of Fangak and Dor on Wednesday, said Col. Philip Aguer, the spokesman for the southern army.
Renegade commander George Athor's troops captured Fangak on Wednesday, and the fighting continued through Thursday until the southern military retook it, Aguer said. No new fighting was reported on Friday.
Aguer said 89 civilians in the two towns were killed, along with 20 southern soldiers and police officers.
Aguer also said 30 of Athor's men were killed. The Associated Press attempted to reach Athor and his top aide for comment but the phone calls to the remote region did not go through.
In September, Southern Sudan President Salva Kiir offered Athor and several other men who had launched armed uprisings against his government amnesty offers.
On Jan. 5, four days before the south held an independence referendum, Athor signed a cease-fire with the army in what then appeared to end one of the largest security threats to the south in the run-up to its self-determination vote.
The independence referendum passed overwhelmingly, according to final results released Monday, and Southern Sudan is set to become the world's newest nation in July. The vote was the culmination of a 2005 peace agreement that ended more than two decades of war between north and south Sudan.
"We were preparing for peace and we don't know why he is waging war at the time when war has ended in Sudan," Aguer said. "Meanwhile we still maintain the spirit of reconciliation because the amnesty is still holding. So if Athor stops fighting we will welcome him for reconciliation."
A U.N. spokesman, Kouider Zerrouk, said Friday that the U.N. mission in Sudan "is very concerned about the renewed fighting ... and the resulting civilian casualties."
U.N. leaders have engaged both sides and are urging an immediate end to the attacks, Zerrouk said.
Last week in Upper Nile state, which borders Jonglei, more than 60 southern soldiers who are members of the northern Sudanese army died in a mutiny related to the imminent breakup of the country.
Ongoing insecurity, the widespread presence of small arms, and severe underdevelopment due to decades of civil war are just some of the problems facing Southern Sudan in the run-up to its independence declaration.
The aid group Doctors Without Borders said Friday it was responding to a huge influx of wounded patients. About 50 patients have been admitted to its health facilities.
"We are mainly seeing patients with gunshot wounds, and many have significant abdominal and limb injuries," said Tim Baerwaldt, head of mission in Southern Sudan.
Medical supplies and personnel have been flown to Malakal, the major town in Upper Nile state, the medical group said.