It happened even as neighbouring nations at a meeting in Thailand were discussing efforts to end the conflict peacefully.
The capture on Thursday by the Arakan Army of a strategically important regional army headquarters in Rakhine state would put it a step closer to seizing control of the entire state, a goal not achieved by any of the several other rebel groups in other parts of Myanmar.
Rakhine has become a focal point for Myanmar's nationwide civil war, in which pro-democracy guerrillas and ethnic minority armed forces seeking autonomy battle the country's military rulers, who took power in 2021 after ousting the elected government of Aung San Suu Kyi.
The apparent fall of the military's western command headquarters is the latest in a series of significant setbacks for the military government that began more than a year ago when a rebel alliance including the Arakan Army captured military bases, command centres, and strategic towns and cities along the Chinese border in Shan state in northeastern Myanmar.
A powerful rebel group in western Myanmar has claimed a major victory against the military junta. (AP PHOTO)
In August, the Myanmar National Democratic Alliance Army, another force in the rebel alliance, was the first group to seize a regional command headquarters, in the city of Lashio in the northeast. Myanmar's military has 14 important regional commands across the country.
Khaing Thukha, a spokesperson for the Arakan Army, told The Associated Press his group had "completely captured and controlled the entire western regional military headquarters based in Ann township" on Friday at noon.
Most of the township was captured two weeks ago, leaving the headquarters encircled. The headquarters' deputy commander, Brigadier general Thaung Tun, and its chief operating officer, Brigadier general Kyaw Kyaw Than, were among those taken prisoner, Khaing Thukha said.
The headquarters had overseen operations in Rakhine and the southern part of neighbouring Chin state, as well as Myanmar's territorial waters in the Bay of Bengal.
The military government issued no news about the latest development, which could not be independently confirmed, because access to the internet and mobile phone services in the area is mostly cut off.
The Arakan Army in its past official announcements has generally been conservative in its victory claims.
The Arakan Army is the well-trained and well-armed military wing of the Rakhine ethnic minority, and seeks autonomy from Myanmar's central government.
In September it launched its effort to capture Ann, about 395 kilometres northwest of Yangon.
It began its offensive in Rakhine in November 2023 and has gained control of 13 of 17 townships, along with one in neighbouring Chin state.
Rakhine, formerly known as Arakan, was the site of a brutal army counterinsurgency operation in 2017 that drove about 740,000 minority Rohingya Muslims to seek safety across the border in Bangladesh.
The Arakan Army has made extensive use of social media to document its operations and in recent days has used it to encourage the army's holdouts at the headquarters to surrender.
28°C