The Arakan Army (AA) says it seized Light Infantry Battalion 380 headquarters in Minbya Township, Rakhine State, on Sunday.
Fighting continues with junta forces in Mrauk U, Kyauktaw and Rathedaung townships, according to the AA.
“The junta is no longer able to compete with us and is using more shelling and airstrikes,” said the group’s statement.
It said historic Mrauk U was being shelled by Light Infantry Battalion 377 and 540 and from Police Battalion 31.
Shelling on Saturday reportedly killed four Mrauk U Township residents and injured at least 20 people, according to the AA.
Junta artillery and airstrikes have been targeting Ramree Township for over a week, although no fighting has been reported, according to residents.
Clashes were reported in Buthidaung Township on Saturday and the AA said junta troops were injured.
Light Infantry Battalions 232 and 344 based in Sittwe, the state capital, shelled Sittwe and Minbya townships.
At least three Khwa Sone villagers in Minbya Township were severely injured by shelling, according to residents.
The AA seized Pauktaw town on January 24 but junta airstrikes and shelling continue. On Saturday night a Y-12 military transport plane bombed the town, according to the AA.
Since the resumption of fighting in Rakhine State in November, the AA has also seized Paletwa Township in southern Chin State and more than 160 junta positions across northern Rakhine State and Paletwa Township.
The Arakan Army is part of the Brotherhood Alliance which launched the successful Operation 1027 in northern Shan State on October 27.