( CNN ) -- More than 40 people have been killed in clashes between soldiers and a rebel militia in Southern Sudan , an official there said Monday , disputing rebel claims they have killed many more government troops . Rebel leader George Athor has been saying his forces have killed more than 100 people , most of them soldiers , since a fresh round of fighting started last week . But Philip Aguer , a spokesman for Southern Sudan 's military , said Athor 's claims are exaggerated . Athor took up arms in 2010 when he was not elected governor of Southern Sudan 's Jonglei state . His forces have been attacking villages and clashing with the Sudan People 's Liberation Army , the military wing of the movement that governs Southern Sudan . People in the region voted overwhelmingly for independence from the north in a recent referendum , setting the stage for Southern Sudan to become a new country . Athor 's forces attacked the towns of Fanjak and Bor a month ago , Aguer said at the time . Twenty SPLA soldiers , 39 civilians and 30 of the attackers were killed in the attack on Fanjak , he said . Four SPLA soldiers and 12 attackers died in the Bor attack , he added . The clashes took place February 9 and 10 , he said . Athor has accused the Southern Sudan government of election fraud , but signed a truce in January , days before the referendum . As the nation readies for official independence on July 9 , violence caused by renegade militias has been a concern . A mutiny among the Joint Integrated Units ( JIUs ) led by soldiers loyal to militia leader Gabriel Tang resulted in up to 50 deaths in February . Sixty-five civilians were also injured . The JIUs are a coordinated military force consisting of the northern Sudanese Armed Forces ( SAF ) and the southern SPLA . Tang 's forces had been merged into the units along with SAF . Journalist Ismail Kamal Kushkush in Khartoum , Sudan , contributed to this report .
Rebels claim they have killed more than 100 people , mostly soldiers , since last week . A Sudan People 's Liberation Army spokesman calls the number exaggerated . Forces loyal to George Athor have been fighting since last year . Southern Sudan voted for independence earlier this year .