The United States has launched an investigation into allegations that a number of American soldiers were responsible for the "unlawful deaths" of at least three Afghan civilians, the US military said on Thursday.
"There are also allegations of illegal drug use, assault and conspiracy," the military said in a statement, adding that while no charges had yet been laid, one soldier was in pre-trial confinement.
The United States, which has the bulk of some 140,000 foreign troops in Afghanistan, has been criticised several times by rights groups and Afghans for maltreating civilians and torturing suspected militant prisoners.
"United States forces Afghanistan has launched a criminal investigation into allegations that a small number of US soldiers were responsible for the unlawful deaths of as many as three Afghan civilians," the statement said.
The US army's criminal investigation command began an investigation after receiving credible information from the soldiers' unit earlier this month, it said.
Further details were not immediately available.