KHARTOUM - At least 57 people were killed and many others were injured in armed clashes between Sudan People's Liberation Army (SPLA) and defecting forces in south Sudan's Upper Nile State, UNMIS radio Miraya FM reported Sunday.

"The SPLA forces have managed to kill 57 soldiers of defector Gabriel Tang in Upper Nile State," Miraya quoted SPLA spokesman Malak Owen as saying.

Owen said his forces attacked Tang's soldiers after they refused to hand over their arms despite the pardon issued by the south Sudan government for the arms carriers, according to the report.

The armed clashes which broke out during the past days between the SPLA and the defecting militia in various areas in south Sudan have resulted in the displacement of thousands of civilians in the region.

Meanwhile, south Sudan's Unity State has witnessed violent clashes between the SPLA and the militia of defector Peter Gadet, which forced thousands of civilians to flee the battle area.

Local officials' preliminary estimations indicated that at least 3,800 civilians, most of them from Mayoum town in Unity State, have abandoned their homes because of the battles.

The clashes started on Tuesday when the southern Sudanese militia, led by Gen. Peter Gadet, attacked the SPLA's Manken camp.

The SPLA earlier said it has restored control over Manken camp in Unity State after battles between its troops and the defectors that killed 12 of its forces.

The SPLA accuses Khartoum of arming southern Sudanese defecting militia to destabilize south Sudan, while Khartoum denies the accusations as baseless.

A number of SPLA military factions have recently declared their rebellion and said they intended to overthrow the south Sudan government because of what they said "spreading corruption at top levels."