The NATO-led International Security Assistance Force (ISAF) has claimed responsibility for killing nine Afghan children in eastern Kunar province and rendered apology for the mistake, a statement of the alliance released on Wednesday said.

"Preliminary findings from a Joint Incident Assessment Team indicate that International Security Assistance Forces accidentally killed nine civilians in Darah-Ye Pech district, Kunar province yesterday," the statement added.

The incident, according to the statement, occurred following insurgent rocket attacks on the coalition forces and the returned fire at the assessed point of origin with indirect and aerial fire.

"Regrettably there appears to have been an error in the hand- off between identifying the location of the insurgents and the attack helicopters that carried out subsequent operations," the statement said.

"We are deeply sorry for this tragedy and apologize to the members of the Afghan government, the people of Afghanistan and most importantly, the surviving family members of those killed by our actions," said General David. H. Petraeus, Commander of International Security Assistance Force in the statement.

"These deaths should have never happened and I will personally apologize to President Karzai when he returns from his trip to London this week," NATO's top commander said in the statement.

General Petraeus in the statement also stated, "Regardless of the outcome of this investigation, I have ordered all ISAF leaders and members of ISAF attack helicopter crews to be re-briefed on the tactical directive, reinforcing the need to be sure we protect the lives of innocent Afghans as we pursue a ruthless enemy."

Earlier, President Hamid Karzai in a statement released by his office on Wednesday strongly condemned the incident.

"The air strike by the NATO that killed nine innocent children and injured another in Kunar happens in less than ten days from a similar attack that left many civilians dead in the same province. The children were collecting firewood when attacked," the statement added.

In the statement, the Afghan president who is currently visiting Britain underlined that "fighting terrorism in Afghan villages can have no success, but casualties of poor and innocent civilians have continued on daily basis due to the unjustifiable operations and bombings carried out by the NATO and ISAF."

"I, therefore, once again remind with emphasis that NATO needs to focus on the safe havens of terrorists, or else killing innocent civilians would create them huge problems," Afghan President noted in the statement.

President Karzai has instructed security agencies and local officials to further investigate the circumstances of the incident and report back to his office in its earliest.