Deadly fighting erupted on Saturday between rival factions of South Sudan Vice President Riek Machar's SPLA-IO, his military spokesman said in a statement.
The clashes erupted after Machar's rivals declared this week they had deposed him as the head of the party and its military forces.
Armed forces led by a rival general in the party, Simon Gatwech Dual, had launched an attack on Machar's men, who had "repulsed the aggressors", the spokesman Colonel Lam Paul Gabriel said.
Machar's SPLA-IO forces had killed two major generals and over 27 "enemy" soldiers, while they had lost three men, he added.
The fighting could not be independently confirmed and there was no immediate response from Gatwech Dual's side.
Leaders of the military wing of Machar's SPLM/A-IO said Wednesday they had deposed the rebel-turned-politician for failing to represent their interests.
The fighting could put pressure on the fragile 2018 power-sharing deal between Machar and his old foe President Salva Kiir.
Machar's allies on Friday dismissed his ouster as a "failed coup", insisting he was still in full control of the party.
Machar himself this week accused "peace spoilers" of engineering his removal.