A Nato investigation into an air strike that killed 24 Pakistani soldiers concluded that both alliance and Pakistani forces made mistakes in the incident, Nato said on Thursday.
Nato's military chain of command voiced its "sincerest, heartfelt condolences to the families" of the victims, the alliance said in a statement following the November 25-26 incident which has severely strained US-Pakistani relations.
"The investigation has ascertained that a series of mistakes were made on both sides in failing to properly coordinate their locations and actions, both before the operation and during the resulting engagement," Nato said.
It said that Afghan and Nato-led forces "legitimately responded in self-defence" after being initially fired upon by "unidentified forces" that were not believed to be Pakistani military at the time, the alliance said.
"The combined force did not knowingly fire at the Pakistani forces," it said.
"The investigation has substantiated that close air support was employed in self-defence in response to intense, heavy machine gun and mortar fire initiated by what turned out to be Pakistan forces near the border in the vicinity of Salala."