At least eight women have died in a Nato air strike in Afghanistan's eastern province of Laghman, local officials say.
Nato has conceded that between five and eight civilians died as it targeted insurgents, and offered condolences.
The remote region in which the strike took place is out of the reach of central government, correspondents say.
Earlier on Sunday, four soldiers with the Nato forces were killed in an attack by suspected Afghan police.
The attack in southern Zabul province brought to 51 the number of Nato troops killed in "insider attacks" this year, and came a day after two UK soldiers were killed at a checkpoint by a man in police uniform.
Local officials in Laghman told the BBC at least eight women had died, while provincial council member Gulzar Sangarwal said nine were dead.
Major Adam Wojack, a spokesman for the Isaf international forces, said between five and eight civilians could have been killed, and said an investigation was under way.
He told the BBC that a group of some 45 insurgents had been targeted by an Isaf unit, and many had been killed.
"Unfortunately, we have become aware of possible Isaf-caused civilian casualties as a result of this strike, numbering five-eight Afghans," he said.
"Isaf offers its sincerest condolences to the affected community and family members, as well as to the Afghan people, concerning this tragic loss of life."
The Laghman governor's office said a number of civilians had gone to the mountains to collect wood and nuts from a forest in the Noarlam Saib valley, a common practice in the area.