Scores of people have been killed in a militia attack on a town in southern Sudan, focusing new attention on warnings that peace in the region remains fragile in spite of the 2005 peace accord which ended the north-south civil was in the country.

The Sudan Tribune reported from Bor on Tuesday that 76 people were confirmed dead in an attack in Jonglei state, which the news service said had been launched on people of the Dinka Bor ethnic group. But Agence France-Presse quoted a spokesman for the south's Sudan People's Liberation Army (SPLA) as saying the death toll was more than 100.

"There is a total of 102 killed, including 51 civilians and 23 of the attackers, and 46 injured," Major General Kuol Diem Kuol told AFP.

The Tribune said south Sudanese authorities refused to name those responsible for the attack. But the agency said similar attacks had been carried out in recent months by a "self-made commander, Chibetek Mabil" from the Lou Nuer ethnic group.

It suggested the attack was part of fighting between people of different ethnic groups over cattle and control of pastures. But it also quoted United Nations and South Sudan officials as saying the attackers were well-equipped and organized, and that the assault on the town, Duk Padiet, was "substantial."

South Sudanese Minister, Gier Chuang Aluong, said it did not appear to be a cattle raid. "We believe it is motivated or encouraged by elements we cannot pin-point,” he said.

The Tribune said Chibetek Mabil was believed to be a former militia member who did not join either the SPLA or the Sudan Armed Forces after the signing of the 2005 peace accord.