Sudanese rebels said they captured a garrison in conflict-hit South Kordofan and killed 54 troops Saturday, with the army denying the claim.
Khartoum has been battling the Sudan People's Liberation Army-North (SPLA-N) in the southern Blue Nile and South Kordofan states since 2011.
The SPLA-N "attacked and liberated Habila town garrison" in the north of South Kordofan on Saturday, with retreating government troops leaving 54 dead behind them, SPLA-N spokesman Arnu Lodi said in a statement.
But Sudanese military spokesman Colonel Al-Sawarmy Khaled Saad said the army had "repulsed a sabotage attempt" in Habila.
Troops "forced the rebels out and are in complete control of the site," Saad said.
He added the attack had "targeted innocent citizens and destroyed their buildings and burned the market" in the town.
Access to the war-torn area is restricted, making it difficult to verify casualties.
SPLA-N troops mounted an uprising in Blue Nile and South Kordofan against Khartoum's Arab-dominated government in 2011, complaining their regions were being marginalised.
In November, Khartoum announced an offensive against the SPLA-N and rebels in the western region of Darfur.