A NATO military report says some members of a U.S.-trained police force in Afghanistan have committed human rights abuses, but that overall the force has been effective.

The NATO report follows a Human Rights Watch study released in September, documenting abuses, including killings, sexual assault, and illegal detention, committed by the Afghan Local Police, or ALP.

The NATO investigation looked at 46 accusations from the HRW report and found seven were credible, 15 were partially credible, while 10 were not credible.

The NATO study conceded the ALP needs better training in basic human rights.

Both NATO and the HRW also raised concerns about the role of government-backed militia groups, known as arbakai, controlled by local strongmen.

Afghanistan's security forces have grown to over 300,000 and receive billions of dollars of funding from the United States.