BANGKOK (AP) — Myanmar ’s 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 U.N. investigation said in a report Tuesday.Separately, a major ethnic armed group fighting the government in Rakhine state said 20 civilians had been killed in strikes by the military so far this month.Myanmar’s military government did not immediately respond to either the U.N. 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.The report by the United Nations-established Independent Investigative Mechanism for Myanmar, or IIMM, details a yearlong investigation into alleged war crimes and crimes against humanity committed by Myanmar’s 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 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.The IIMM said 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.