A human rights group in Myanmar says as of Tuesday, 521 people have been killed by the military's crackdown on protesters following the recent coup.
Demonstrations continued in the largest city of Yangon and elsewhere, with protesters taking to the streets in small groups and some blocking residential roads.
The military conducted airstrikes against ethnic minority armed forces in the southeastern state of Karen for a fifth straight day, as they joined in protesting the military coup.
The armed group said it is taking care of some 2,000 protesters who fled from military crackdowns in urban areas.
The military has sent thousands of ground troops there. Amid growing fears of a showdown with the armed group, about 10,000 residents are reported to have started evacuating. Many of them are said to have crossed the border into neighboring Thailand.
Local media reported that ethnic armed forces attacked a military post in the northern state of Kachin on Wednesday, following a similar attack on Sunday.
Three other armed groups on Tuesday issued a joint statement threatening to join the protesters' fight to protect civilians.