A NATO airstrike killed ten Afghan civilians, including five children, in eastern Afghanistan, according to local officials.
If the death toll is confirmed, it is likely to raise tension between President Hamid Karzai's government and US-led NATO forces.
The strike, in the Shigal district of Kunar province, was confirmed by NATO's International Security Assistance Force, though a spokesman said it could not confirm civilian casualties.
"Foreign forces carried out the attack by themselves without informing us," Kunar Governor Fazlullah Wahidi said.
Four Taliban fighters were also killed in the strike and five civilians wounded, he said.
The strike occurred in the village of Chawgam and the ten dead civilians are believed to be from two local families.
A spokesman for ISAF, Major Adam Wojack, said he was aware of an incident that "matched" the report from Kunar, but he could not confirm casualty numbers.
"We take all allegations of civilian casualties seriously and we are currently assessing the incident to determine more facts," Major Wojack said.
ISAF regularly states that it has reduced civilian casualties in recent years, and that the insurgents are now responsible for 84% of all such deaths and injuries.
The airstrike came within hours of US President Barack Obama's declaration that he would be withdrawing half the US troops in Afghanistan - 34,000 - by the end of this year.
That would be followed by further troop withdrawals next year, which would lead to the end of the US war in Afghanistan, he said.