A Nato helicopter has reportedly killed two children in south-east Afghanistan after opening fire on Taliban fighters.
Nato spokesman Major Adam Wojack said the police officers had come under attack from insurgents while on patrol.
When called in, he said, the helicopter opened fire on the insurgents. He added that International Security Assistance Forces was investigating reports of civilian casualties.
Nine Taliban fighters were killed and eight civilians were wounded, according to senior Afghan police detective Colonel Mohammad Hussain.
A Reuters reporter saw the bodies of two children, whom local people said had been killed in the air strike.
On 13 February, 10 Afghan civilians in Kunar province, including five children, were killed by a Nato airstrike.
Following that attack, Afghan President Hamid Karzai barred local forces from seeking air support from foreign troops in an attempt to prevent civilian casualties.
And earlier this month, Australian soldiers killed two children who were tending cattle, during a firefight in the southern Uruzgan province.
Civilian casualties caused by air strikes are a significant source of friction between Karzai and his international allies as Washington and Kabul negotiate over the size of a future US military presence after most international troops depart by the end of 2014.
Some Afghan officials say privately that limiting air strikes exposes the 352,000-strong Afghan security forces to greater danger as they take over the responsibilities of international forces.