The headquarters of the Karen National Union (KNU), a major military base in Hpa-an district, Karen State, was bombed by suicide drones in the early hours of June 12, a military source told the BBC.
The drone strikes took place between 1am and 4am, he said.
“There were no casualties,” a headquarters official said.
The attack was carried out by the military, which had been forced to abandon its bases in the area, but the BBC could not independently confirm this.
The military also carried out three drone and air strikes on the headquarters of the Karen National Union (KNLU) in mid-March.
Meanwhile, the Karen National Liberation Army (KNLA) and the People’s Defence Force (PDF) have been carrying out attacks on military positions in the area.
From March to June, the Karen Revolutionary Joint Forces captured at least 10 military council posts in the 7th Brigade area, including the Tse Baw Boe Ma Setam defensive post on the Thai-Burma border, which is crucial to the Burmese military’s border defenses.