Australian military chief General David Hurley Sunday said he deeply regretted the deaths of two Afghan boys killed during an operation but it was too early to say who was responsible.
Two children, aged seven and eight, were shot dead on Thursday as they tended cattle in southern Uruzgan province, in an incident which could inflame tensions over the conduct of foreign soldiers in Afghanistan.
The NATO-led International Security Assistance Force has admitted its troops caused the unintended civilian deaths and Uruzgan's governor has said Australian soldiers were responsible.
"We deeply regret that the International Security Assistance Force (ISAF) were responsible for the unintended death of two young Afghan boys during the operation," said Hurley, who is chief of the Australian Defence Force.
But he added: "It is premature to make any determination about how the incident occurred or who was responsible."
Hurley said Australian Special Operations soldiers were on the ground conducting a routine liaison patrol when the incident occurred on February 28.
"Australian personnel immediately reported the incident to Afghan government officials and military leaders in Uruzgan," he said in a statement Sunday.
Provincial governor Amir Mohammad Akhundzada told AFP that the children were killed as Australian soldiers fought back after a Taliban attack.
"The children were killed by Australian troops, it was a mistaken incident, not a deliberate one," Akhundzada said, adding that insurgents had first shot at a helicopter carrying Australian soldiers.
ISAF, to which Australia contributes close to 1,100 soldiers, has expressed its "deep regret" over the children's deaths, saying its troops had opened fire at what they believed were insurgent forces.
The Australian Defence Force said its commanders were working with their ISAF and Afghan colleagues to determine the facts surrounding the incident.
It said it took the issue of civilian casualties very seriously and its personnel operated under a strict set of Australian rules of engagement designed to minimise the risk of civilian casualties.
As the incident was now under investigation, it would not comment further, it added.
Civilian casualties caused by NATO-led forces have been one of the most contentious issues in the campaign against Taliban insurgents, often triggering widespread public anger and harsh criticism from President Hamid Karzai.
The bulk of Australia's 1,550 troops are based in Uruzgan, and are focused on training and mentoring Afghan soldiers ahead of the withdrawal of NATO combat troops by the end of next year.