An end to air strikes in Afghanistan, as demanded by President Hamid Karzai after scores of civilians were allegedly killed, would deprive Afghan troops of important protection, a US official said on Friday.
"Airstrikes are not acceptable," Karzai said on Friday during a visit to Washington, adding that his government's information was that nearly 125 to 130 civilians were killed, including women and children, in this week's strikes.
The US military in Kabul was expected to release on Saturday results of its investigation with the Afghan defence and interior ministries into the incident in the western province of Farah overnight Monday into Tuesday.
US officials said however they believed a figure of more than 100 people killed was "exaggerated".
The air strikes in Farah were called in at the request of Afghan officials who were under attack from Taliban fighters.
"This was not a night raid, this was not a scheduled operation, we came to their assistance," a US official said on condition of anonymity. "We were supporting our Afghan partners."
With an end to protection from air power, "more of the well-trained Afghan National Security Forces are going to be put in harm's way with very little assistance."
There has been no admission from the US military that it killed civilians in the strikes, which locals said destroyed several houses in two villages in the Bala Buluk district where insurgents have a strong presence.
A report in the US media, citing Pentagon officials, said US forces dropped about 13 bombs on eight different buildings from which troops were taking fire.