Fighting between northern and southern soldiers broke out yesterday in Heiban town of Nuba Mountains.
The SPLA took over the area and there were many casualties among civilians and soldiers from both sides, Voice of Peace Radio reported.
The SPLA lost more than ten fighters.
The casualties among northern forces, including police, were very heavy.
Few people were buried.
Many were disposed in pit latrines as mass graves and others left in the bush between Heiban and Al-Lazrag.
Some cattle keepers who took refuge in the bush said many wounded died before reaching Al-Lazrag.
Some SAF soldiers surrendered to the SPLA after the fight.
Many civilians managed to leave Heiban before the battle.
Heiban is almost empty and the security situation is still due to air force bombardments.
On Thursday evening two MIG jets bombed the eastern part of Kichama.