US military officials concede civilians may have been killed during Friday's bombing raids on a suspected Taleban hideout in eastern Afghanistan.
The US says it attacked immediately after receiving intelligence
US fighter planes carried out the bombing in the Kunar province where US servicemen have been missing.
US military sources say militants were inside the residential compounds but innocent civilians may have died.
An Afghan official told the BBC US planes started fresh raids on Sunday in Nangalam valley in the province.
The unnamed official said Afghan troops on the ground were facing serious resistance.
However a spokesman at the US military headquarters at Bagram near Kabul said he had no information about the operation.
More than 500 people, most of them suspected militants, are now estimated to have lost their lives in bloodshed in the south and east in the past three months.
Violence has been escalating in Afghanistan ahead of parliamentary elections due in September.
US military spokesman Lt Col Jerry O'Hara said about Friday's air raid: "We conducted an air strike on a target we deemed we had to hit immediately."
Lt Col O'Hara told AP news agency the air strike was carried out with precision-guided weapons on a target that was "intelligence driven".
It is possible that the decision was taken to go ahead despite the likely risk of civilian casualties, says the BBC's Andrew North, who's in eastern Afghanistan.
More than 500 people have died in the past three months
A high-ranking Afghan security official in the province, speaking on condition of anonymity, told the BBC there had been two separate bombing runs on Chechal village.
He said 25 people had been killed.
Villagers who went to help those killed and injured in the first raid were hit by the second strike, he said.
The official said security forces had been sent to the area to find out who had been in the houses that were hit.
Officially, the US military says it is still conducting a battle damage assessment of the site.
The US will not say if the bombing was connected to the ongoing search for the missing special forces team who disappeared on Tuesday when they were on a reconnaissance mission.
A helicopter which was sent to pick them up was shot down, killing 16 servicemen on board.
Additional US troops have been sent to Kunar province as part of a new operation - Operation Flier - against militants in the region.