Amnesty International reported on Friday that Myanmar's military employed a sizable unguided aerial bomb in a fatal assault on a camp where displaced individuals were sheltered in the northern region of the country.
The ruling junta has been accused of carrying out multiple bloody attacks on civilians as it struggles to crush resistance to its 2021 coup.
The latest incident on Monday night saw 29 bodies and 56 wounded pulled from the debris at a camp near the northern town of Laiza, on the border with China, according to the Kachin Independence Army (KIA) ethnic rebel group.
An Amnesty International weapons expert analyzed photos and videos of the aftermath of the attack that "show evidence of a single massive blast that flattened dozens of nearby buildings – including a church, preschool and many homes – and started fires".
"The size of the crater and observed damage is consistent with the largest aerial-delivered bombs known to be in the inventory of the Myanmar military," the rights group said.
"Amnesty International believes the Myanmar military almost certainly used an unguided bomb, which is an inaccurate weapon completely inappropriate for use in the vicinity of civilians."
The statement said the incident "may amount to a war crime."
"The blast wave caused catastrophic overpressure and fragmentation injuries to the victims, including fatal wounds to heads, lacerations that exposed organs, and the removal and pulverization of limbs," the rights group said.
The junta had said bombs belonging to rebels in the area caused the explosion without giving evidence.
But Amnesty International said the military's "explanation is at odds with consistent witness accounts, which noted the explosion served as the start of a coordinated attack".
"The bomb fell on a large open field with regular vehicle traffic, unlikely to be an ammonium nitrate storage area," the rights group added.
The KIA controls large parts of the Christian-majority Kachin state and has clashed with Myanmar's military for decades.
The region has seen intense fighting since the coup, and the junta accuses the rebels of training People's Defense Forces that have sprung up in resistance.
The United Nations Secretary-General Antonio Guterres said he was "alarmed" by the incident and that "those responsible must be held to account".
