The Burmese military has increasingly used low-cost aircraft such as motorized paragliders and gyrocopters in escalating aerial attacks that kill civilians in its conflict with armed, anti-government groups, a UN investigation said in a report released on Tuesday. Separately, a major ethnic armed group fighting the government in Rakhine state said that 20 civilians had been killed in strikes by the military so far this month. The Burmese government did not immediately respond to the UN probe or the allegations by the Arakan Army. In the past, the military has said it only attacks legitimate targets of war, accusing the resistance forces of being terrorists.

A man clears debris after an airstrike by the Burmese military in Kyauktaw in Myanmar’s Rakhine state on June 18.

The report by the Independent Investigative Mechanism for Myanmar (IMM) details a year-long investigation into alleged war crimes and crimes against humanity committed by the Burmese military and affiliated militias, as well as the opposition armed groups. It found that abuses escalated around the country’s army-organized elections in December last year and January.

The IIMM said it observed a notable escalation in aerial attacks in the months preceding the elections and that they have continued unabated afterward, with investigators also documenting a pattern of deliberate arbitrary detention, torture and sexual violence. Civilian casualties are worsened by the military’s increasing use of “double-tap” aerial attacks, in which a second strike follows the first, apparently targeting first responders, people helping the wounded and those trying to flee, the IIMM said. The Burmese military was increasingly using motorized paragliders — also known as paramotors — as well as gyrocopters and drones to carry out low-altitude airstrikes with unguided explosives, the report said. In incidents in the upper Sagaing region, paramotor pilots allegedly cut their engines as they approached targets, allowing them to glide silently and leaving civilians little or no warning to flee or seek shelter, it said. The report came as the Arakan Army, a powerful ethnic armed group fighting the army in Rakhine, said that about 20 civilians were killed and 22 injured in airstrikes across three townships from Aug. 1 to Tuesday, including one attack involving up to eight aircraft that lasted about an hour.