The NATO-led force in Afghanistan has said it will investigate an airstrike that local officials say killed a child further aggravating a stand-off between the Afghan president and the US government.
Afghanistan's President Hamid Karzai said the killing demonstrated the US did not respect the lives of Afghan civilians and, if such attacks continued, he would not sign a bilateral security pact.
This attack shows American forces are not respecting Afghan lives... As long as unilateral acts and atrocities continue by American forces on our people, we won't sign this [Bilateral Security Agreement].
The NATO coalition acknowledged reports of the boy's death and said it “deeply regrets any civilian casualties" caused by Thursday's airstrike in Helmand, a hotbed of the Taliban insurgency.
"ISAF deeply regrets any civilian casualties caused by this airstrike," the force said in a statement on Thursday.
The strike was launched from an unmanned drone and hit the village of Faqiran, the statement said.
NATO's International Security Assistance Force said that the strike targeted a fighter riding a motorbike but did not confirm that a drone was involved.
Helmand provincial spokesman Omar Zwak told the AFP news agency that the airstrike had targeted a Taliban commander but had instead killed a child called Rafiullah. Zwak said a second drone attack killed the commander.
Wrangling over the security deal has lasted about a year. The pact aims to shape a US military presence in Afghanistan after 2014, when most foreign forces are due to leave the country.
Without a pact, US officials have warned Washington could pull out all of its troops.
Karzai, in a statement, said he "strongly condemns the airstrike by NATO forces on a house which killed one child and wounded two women."
"This attack shows American forces are not respecting Afghan lives... As long as unilateral acts and atrocities continue by American forces on our people, we won't sign this [Bilateral Security Agreement]."
Karzai, who is due to step down ahead of presidential elections in April, has been stalling over the security pact that would see some US troops to remain in Afghanistan after next year for training and counter-terror missions.
About 75,000 NATO combat troops still deployed in Afghanistan are due to withdraw by the end of 2014 after fighting the Taliban since the group were forced from power in 2001.