Myanmar has been in turmoil since a February coup ousted Aung San Suu Kyi's elected government, sparking huge protests and renewed clashes between the military and ethnic rebel armies in border regions.

State media published pictures Monday showing what it said were the bodies of 25 construction workers massacred by fighters from the Karen National Defence Organisation in the east of the country.

The group is part of the Karen National Union -- a prominent ethnic armed group that has fought the military for decades and which had condemned the generals' coup.

"There have been media reports spreading since June 13th that 25 civilians... were killed by KNDO on May 31st, 2021," the KNU said in a statement.

"KNU (central) will form an investigating team to investigate to reveal the truth."

The group added it "cannot accept killing of civilians during fighting... We also have our restrictions to take action according to our related law regarding this kind of cases."

Since the coup the KNU has clashed sporadically with the Myanmar military along the Thai border.

In March its fighters seized a military post and the army retaliated with air raids, the first in more than 20 years in Karen state.

On Wednesday Myanmar's junta and villagers in the central Magway region traded accusations after a settlement was razed almost entirely to the ground.

Villagers of Kin Ma told AFP junta forces were to blame for its near-destruction, while the junta's information team told journalists "terrorists" and windy weather were responsible.

The military has sought to quell mass anti-coup protests with bloody crackdowns that have killed more than 850 civilians, according to a local monitoring group.

Junta leader Min Aung Hlaing has justified his power grab by citing alleged electoral fraud in the November poll won by Suu Kyi's National League for Democracy.