An alliance of ethnic armies in Myanmar on Saturday attacked a police station in northeastern Shan state, killing at least 10 officers, local media reported.
Fighters from the Arakan Army, the Ta'ang National Liberation Army and the Myanmar National Democratic Alliance Army, who oppose the country's military crackdown on anti-coup protests, attacked Naungmon police station.
Shan News reported that at least 10 policemen were killed, while the Shwe Phee Myay news agency put the death toll at 14.
About a dozen armed groups have condemned Myanmar's military as illegitimate and pledged to stand with the country's protesters as violence intensifies, opening up the prospect of a much deadlier civil war.
The militias have waged separate insurgencies against the junta since the end of British rule in 1948.
Death toll surges in junta crackdown
Reports also emerged Saturday of deadly violence in the city of Bago, 65 kilometers (40 miles) northeast of Yangon.
A daylong crackdown by government troops and police in the city forced many residents to flee to nearby villages.
About 10 people were killed, the Bago Weekly Journal Online reported, citing a local source.
Other media reports have put the death toll in Bago far higher.
A resident told French news agency AFP that at least 40 protesters were killed in the crackdown.
"They piled up all the dead bodies, loaded them into their army truck and drove it away," he said, adding that authorities then arrested several people around the community.
AFP-verified footage shot Friday showed protesters hiding behind sandbag barricades with homemade rifles as explosions could be heard in the background.
Military violence was also reported Friday in several other areas, including Loikaw, the capital of Kayah state in the east, where live ammunition was said to have been deployed.
UN ambassador urges concrete action
In response to the uptick in violence, Myanmar's ambassador to the UN appealed for a no-fly zone, an arms embargo and more targeted sanctions against junta members and their families.
"Your collective, strong action is needed immediately," Ambassador Kyaw Moe Tun told the UN Security Council meeting on Friday.
"Time is of the essence for us," he said. "Please, please take action."
The International Crisis Group also warned the council that Myanmar was "at the brink of state failure."
At least 614 protesters and bystanders have been killed by the military in the crackdown on protests against the February 1 coup, according to the watchdog Assistance Association for Political Prisoners.