A team of United States and Afghan investigators are due to announce the results of an investigation into last Monday's air-raid by the U.S. in which up to 46 civilians were killed. 22 of the dead were attending a wedding.
The U.S. said that that the bombing raid on villages in the central province of Uruzgan was in response to anti-aircraft fire from the ground.
President Bush has spoken to the Afghan leader, Hamid Karzai. Mr Bush described the deaths of Afghan civilians as a 'tragic loss' and passed on his sympathies to the families of those who died.
The word apology was not used by Washington because for now, there remain differing accounts of what happened on Monday morning.
The Americans insist their planes were simply responding to anti-aircraft fire from the ground.
A team of investigators from both countries has been to the remote region and is due to report its findings soon.
