Australian troops were "unlikely" to be responsible for Afghan civilian deaths during a January battle with insurgents
but their involvement could not be ruled out, a report found Thursday.

Australian Defence Force head Angus Houston said an internal inquiry had found "on the balance of probabilities" that Australian troops had not fired the munitions that caused the four deaths.

The clash between Australian troops and Taliban insurgents, during which the Afghan civilians said they were injured, took place in the Baluchi Valley in southern Afghanistan on January 5.

Houston said one mortar round had overshot its target by up to 60 metres (65.6 yards), but because it had not been detected by aerial surveillance, no firm conclusion about whether it had caused injuries or deaths was possible.

"Due to the lack of aerial observation the possibility that civilian injuries may have been caused by this mission cannot be completely excluded," Houston told reporters.

The inquiry was launched after eight injured Afghan civilians arrived at an international forces patrol base early in the afternoon of January 5, hours after the fight, and told officials they had been hit by mortar fire, he said.

Four of the injured, including a 12-year-old girl with shrapnel wounds to her stomach and head and her younger brother, were immediately airlifted to a Dutch military hospital at Tarin Kowt, in central Uruzgan province, he said. A man in the group died of his injuries that night, he said.

Shrapnel removed from the girl was tested at Australian military laboratories which found "it was not from an exploding mortar round used by the special operations task group," Houston said.

"I can tell you quite conclusively that the fragment that came out of the person who was injured, there's no connection between that piece of shrapnel and our munitions," he said.

During the battle Taliban insurgents had fired a rocket and a grenade which flew over Australian forces toward nearby residential compounds and "that was more likely to have caused the casualties than what we had done," Houston said.

The Afghan civilians had said up to 10 people died in the attack, but the report said only four civilians died, adding the local governor agreed with that number.

The report also said the dead could have been insurgents, rather than innocent local nationals, but added: "No firm conclusion can be reached."

Australia last month committed 450 more soldiers to the conflict in Afghanistan, boosting troop numbers to 1,550.
Since 2001, 10 Australian soldiers have died in Afghanistan - many of them in the past six months - in Uruzgan province, for which Australia has security responsibility.