|South Sudan's SPLA had made a ceasefire deal with George Athor's rebel forces before last month's referendum [EPA]
At least 16 people have been killed in clashes between rebels and the army in south Sudan's Jonglei state, breaking a ceasefire agreed last month, the southern army has said.
Philip Aguer, spokesman for the south's Sudan People's Liberation Army (SPLA), said the violence started when fighters loyal to rebel leader George Athor attacked an army base on Wednesday.
"Four SPLA soldiers were killed and 12 of Athor's men," he said. "This is a violation of the ceasefire agreement. Not only has he attacked SPLA, he has been planting landmines as well."
Aguer said Athor's men attacked two sites in Fangak county on Wednesday afternoon and Thursday morning, and two vehicles carrying SPLA soldiers hit a landmine on Wednesday.
However, Athor told the Sudan Tribune news website that the SPLA had launched the attacks.
Athor is a renegade southern general who launched a rebellion after claiming he was cheated in governorship elections last April in Jonglei.
Call for peace
A ceasefire agreement was signed between the rebels and the army in January, just days before a landmark referendum on secession for the south.
On Monday, final results showed that around 99 per cent of southerners voted to separate from the north. The referendum was held under a 2005 peace deal which ended decades of north-south civil war.
That conflict killed an estimated 2 million people and was also marked by violence between rival southern militias. There have been fears that old divisions could re-surface during the build-up to secession, which is due to take place on July 9.
Southern leaders accused Khartoum of backing Athor when he first revolted but did not repeat the accusations on Thursday.
"We call on George Athor to look at this great moment in our history and make a logical decision for peace," Aguer said.
Southern soldiers in a northern Sudan Armed Forces unit in neighbouring Upper Nile state mutinied last week after refusing to redeploy north as part of a separation of forces before the south's independence. The southern army said on Thursday that the death count from those clashes had climbed to 60.