Forces loyal to the nation's former vice president, Riek Machar, took the Unity state capital Bentiu over the weekend. Government forces known as the SPLA are now looking to take it back.
"The SPLA forces are in the western part of the state and the SPLA is reorganizing. Definitely they will launch an attack on Bentiu any time," army spokesman Philip Aguer said.
The preparations come after a former SPLA Gen. James Koang Chuol defected to the opposition and declared himself governor of Unity. Chuol said the SPLA tried to have him assassinated. Auger denied the allegations, Voice of America reported.
Also in the area, the body count in a mass grave first reported to be found by United Nations peacekeepers has been revised downward, from an initial estimate of 75 to 15 now, official said.