(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.