Rockets and heavy machines guns fired from Afghan government helicopters killed and wounded at least 107 boys and men attending a religious ceremony near the northern city of Kunduz in April, according to a United Nations report.
On April 2, villagers in Dasht-e-Archi district of Kunduz said dozens of people, including many children were, killed in a government air attack on a religious ceremony, prompting the UN to launch an investigation.
In its report on Monday, the UN said at least 36 people, including 30 children, were killed and 71 wounded and there were questions "as to the government's respect of the rules of precaution and proportionality under international humanitarian law".
"A key finding of this report is that the government used rockets and heavy machinegun fire on a religious gathering, resulting in high numbers of child casualties," the United Nations Assistance Mission in Afghanistan (UNAMA) said.
Based on interviews with over 90 witnesses, the report added that the helicopters swooped down, firing rockets and .50 calibre machine guns into a crowd attending a so-called dastar bandi ceremony in Laghmani village, Dasht-e-Archi.
The ceremony celebrates boys who have learned the Koran by heart.
It also underlined the risks of a new strategy, developed with US advisers, which has seen a big build up in Afghan air power, with rocket-equipped helicopters and attack aircraft deployed to try to break a stalemate with the Taliban.
In October 2015, 42 people were killed in a US air strike on a hospital in Kunduz city run by medical aid group Medecins Sans Frontieres.
Investigators verified 107 victims but had received victims' lists from various sources indicating over 200 casualties, the report said, noting that it did not claim to be providing final, verified civilian casualty figures.
It said there were serious concerns about the incident that required further investigation but said it was not in a position to determine whether the attack amounted to a violation of international law.
Last month, the government said the attack was intended to hit members of a senior leadership group based in the Pakistani city of Quetta, who it said were in the area. It also targeted members of a Taliban "Red Unit", or special forces group, that was planning an attack on Kunduz city, which has been overrun by insurgent forces twice since 2015.
It said as many as 12 rockets may have been fired at the meeting, held in a field about the size of a football pitch, which was adjacent to a madrasa.
The helicopters continued to attack as people fled towards nearby roads and houses but the UN could not verify allegations that they deliberately targeted civilians and could not determine the civilian status of each person killed or wounded.
In the wake of the attack, the government acknowledged that civilians had been killed and President Ashraf Ghani ordered an investigation but so far no results have been made public.
While overall civilian casualties this year have remained stable from last year, the UN had expressed concern over the high number of casualties from air attacks even before the Dasht-i Archi incident, with 67 deaths and 75 injuries in the first three months to the end of March.