More than 13 members of the security forces were killed in a clash between fighters, who are opposed to Myanmar's military junta, and the country's troops in the country's east.
The fighters of the People's Defence Force battled early Sunday with security forces in Muse which is one of the main crossings to China, Asia Nikkei reported citing Myanmar media.
The People's Defence Force, which was formed following February's coup, is an alliance of four ethnic armed groups which are also against the coup. They have been attacking security forces.
Early this month, Myanmar's National Unity Government (NUG), set up by opponents of army rule, formed a "people's defence force" to protect its supporters from military attacks and violence instigated by the military government.
On Friday morning, six soldiers, including a captain, were killed in an ambush in Chin State's Falam Township.
Two military trucks carrying reinforcements were attacked while travelling on the Falam-Kalay road, the group said.
"We were defending against reinforcements coming to Hakha. It started at around 8 am. At least six from the military were killed. Their truck was thrown off a cliff," a Chinland Defense Force (CDF) spokesperson told Myanmar Now.
Meanwhile, twelve police officers in the Chin State town of Kanpetlet have defected to join the struggle against the coup regime, a local group of resistance fighters said.
The CDF announced on Saturday that it had taken responsibility for the security of the defectors, who include a sergeant and two lance-corporals and are all ethnically Chin.
In the wake of the February 1 coup, many members of the police force in Chin State left their posts to join the nationwide Civil Disobedience Movement (CDM).
On February 1, the Myanmar military overthrew the civilian government and declared a year-long state of emergency. The military coup led to mass protests and was met by deadly violence, resulting in the killing of more than 800 people. Meanwhile, about 5,200 protesters have also been detained.