A senior regional official says Afghan soldiers were to blame for a mortar strike that killed at least 20 people at a wedding in southern Helmand province.
Seventeen of those killed by mortar rounds on December 31 were women and children, and more than 50 people were wounded.
Mohammad Jan Rasoulyar, deputy governor of Helmand, said troops "fired mortar rounds on a wedding ceremony after the militants in the same area attacked an army checkpoint."
Speaking to AFP news agency on January 2, he said the Afghan army troops accused of firing the rounds "have been referred to a military court."
Four soldiers, including one commander, were arrested and taken to the provincial capital, Lashkar Gah.
Dozens of people demonstrated on January 1 over the bloodbath.
It occurred on the eve of a military ceremony in Kabul at which President Ashraf Ghani congratulated the Afghan army and police for taking over from NATO forces who ended their combat mission at the end of 2014.
Based on reporting by AFP