Myanmar's semi-civilian government, which took power in 2011 after 49 years of military rule, has set a priority on ending hostilities with the many groups that have taken up arms since independence in 1948.
Last month, negotiators from the military and the National Ceasefire Coordination Team, which represents ethnic armed groups, agreed on a nationwide ceasefire draft accord to be discussed at a summit of ethnic rebel leaders next week.
"We were very upset because the government does not recognize our claim to membership in the Nationwide Ceasefire Coordination Team," General Nyunt Htun Aung, the second in command of the Arakan Army, said in a telephone interview.
"The Arakan Army will be more active in Rakhine state in the future since our army is stronger than before," Nyunt Htun Aung told Reuters. "It's time to stand along with our people."
The ranks of the Arakan Army have grown in the past year to more than 2,000, from about 300 fighters, he said, with training received from the powerful Kachin Independence Army (KIA).
It has also joined forces with the Myanmar National Democratic Alliance Army (MNDAA), which launched an insurgency on Feb. 9 alongside other ethnic minority rebel groups, including the KIA.
As ceasefire talks enter a critical phase, Arakan Army leaders decided to take their battle from the northeastern frontier with China to their home in Rakhine state bordering Bangladesh, Nyunt Htun Aung said.
The ethnic minority insurgents have clashed with the military several times over the past few weeks, in Rakhine state's first such battles in about a decade, a military officer in the state told Reuters on Thursday.
The officer, who sought anonymity as he was not authorized to speak to media, confirmed the Arakan Army had killed two government soldiers and detained two. The military captured five rebel fighters last week, state-run newspaper Global New Light of Myanmar said. But Rakhine state government official Hla Thein dismissed the threat from the Arakan Army, calling it incapable of a serious insurgency, such as that in Kokang led by the MNDAA, a well-armed ethnic Han Chinese rebel group. "We don’t need to be afraid of the Arakan Army, because they are only a small group," he said. "They won’t be able to fight like the Kokang rebels."
(Editing by Jared Ferrie and Clarence Fernandez)