The US military investigation found that civilian men, women, and children were "likely inside the buildings from which the Taliban were firing," according to the report released on Thursday.

US and Afghan forces called for reinforcements while battling the Taliban in the village of Boz, in the outlying areas of the city of Kunduz, in November 2016. In response, NATO aircraft targeted houses in the village. The skirmish killed 33 civilians and wounded 27 more, with two US soldiers and three Afghan commandos also killed. According to information published after the strike, 17 of the casualties were children.

"To defend themselves and Afghan forces, US forces returned fire in self-defense at Taliban who were using civilian houses as firing positions," NATO said in the Thursday statement.

In the same strike, a Taliban weapons cache was hit "which also destroyed multiple civilian buildings and may also have killed civilians," they added.

"Regardless of the circumstances, I deeply regret the loss of innocent lives," said General John Nicholson, the commander of US forces in Afghanistan.

UN probing the bombing

The massacre triggered an uproar from the villagers, some of whom piled the dead children onto open trucks and drove them through Kunduz city, or carrying them to the local governor's office in protest.

The UN also launched their own investigation into the incident. Its results are set to be published by the end of January.

The head of the UN Assistance Mission in Afghanistan, Tadamichi Yamamoto, called the loss of civilian life "unacceptable," while activists from other organizations also protested the killings.

Following NATO's withdrawal of combat troops in 2014, no coalition soldiers officially participate in the ground push against the Taliban. Instead, the western troops serve only as advisors to Kabul's security forces. However, the Afghan army and police struggle to contain the Taliban insurgency, with Islamists forces twice overrunning Kunduz in 2016.

dj/msh (AFP, dpa, AP)