The head of information and media at the SPLA General headquarters in Juba, Malaak Ayuen, says opposition forces attacked government bases, an allegation the opposition has denied.
Gen Malaak told Eye Radio that the SPLM in Opposition first started shelling the area on Monday.
On Tuesday morning, he said the opposition forces crossed the Nile River to attack government bases.
“They walked to the market area and….opened fire on our force,” said Mr Ayuen, “and then the fighting took place and they were chased from that area.”
For his part, the military spokesman of the SPLM in Opposition, Dickson Gatluak, said the SPLA were the first to move out of their areas to attack:
“They are the ones in control of Nasir – they started moving out yesterday evening and then this morning they attacked our defensive position in a place called Pananyang.”
Both sides claim they repulsed the other. There are no details on the casualty figures.
SPLA commander in Nasir Peter Wichlual says the fighting ended the same day and the town is now calm.
“The situation in general is normal. Even citizens who had run away are back,” he told Eye Radio.
The acting spokesperson of the SPLA, Lieutenant Colonel Marko Mayo, says he is yet to receive the full report of the casualties.
But on Tuesday, deputy military spokesman Dickson Gatluak said their forces were responding to an attack by the SPLA.