Article published on the 2009-05-09 Latest update 2009-05-09 13:20 TU
After visiting two villages in the district of Bala Buluck, the investigation concluded that civilians had died but declared itself "unable to determine" how many of the dead were Taliban fighters, since the bodies had been buried.
The investigation, which did not make clear whether the dead had been killed by air strikes or ground fighting, is continuing.
The incident reportedly started when Taliban fighters, including non-Afghans, arrived in the villages and demanded money from local people. They also attacked police checkpoints and the provincial government called for military help.
Heavy fighting continued for several hours and international troops called in air support. The investigation claims that the Taliban forced villagers into houses, which they then used to attack the troops.
But villagers told a video report, seen by the AFP news agency, that the bombing started when "there were no Taliban at all". The footage shows men collecting body parts.
"Air strikes are not acceptable," Karzai told the CNN TV channel, saying that his government has information that 125-130 civilians, including women and children, were killed.
The claims have sparked angry demonstrations in Afghanistan and these are not the first protests over civilian casualties from international attacks.
UN officials are reported to be sceptical about claims that the Taliban caused some of the casualties, while US officials claim that the air strikes are needed to defend both Afghan and international troops.