Kabul  - NATO said Thursday that its forces killed six civilians in an airstrike in eastern Afghanistan while the military alliance's top commander in the country said that more efforts would be made to avoid such killings in the future.

Six people, including a woman and children, were killed and 14 were wounded in Monday's airstrike in Kunar province.

In its initial reporting of the incident, the NATO-led International Security Assistance Force (ISAF) said the operation resulted in the deaths only of Taliban insurgents.

But the Afghan presidential palace said in a statement Thursday that NATO's top commander in Afghanistan, US General David McKiernan, admitted to President Hamid Karzai that "despite repeated efforts by NATO and coalition forces, civilians sustained casualties in Khost and Kunar provinces."

"A joint investigation by the Afghan government and ISAF determined that four enemy fighters and six Afghan civilians were killed during the [Kunar] operation," NATO said in a separate statement.

"Four civilians were seriously injured, 10 received minor injuries and a local home was damaged," the statement said.

The presidential statement also said that McKiernan assured Karzai that the alliance would work more closely with Afghan security forces to avoid such incidents.

The NATO forces apologized for the loss of life and offered assistance to the families affected by the operation, the statement said.

During operations in the east-central province of Khost on April 8, five civilians, including two women and a 7-day-old child, were killed. The ISAF had earlier admitted those killings and apologized.

Civilian casualties have become a delicate issue in Afghanistan. Karzai has repeatedly pleaded with international forces to avoid civilian killings during their anti-insurgent operations.

Afghan civilians have borne the brunt of the conflict in the seven years following the fall of the Taliban regime. More than 2,100 civilians were killed in the conflict last year, the United Nations said.

Meanwhile, an ISAF soldier was killed Wednesday in a roadside bombing in eastern Afghanistan, the alliance said in a statement Thursday.

The statement did not disclose the nationality of the deceased, but most of the troops stationed in the eastern region of the country are from the United States.

Nearly 60,000 troops are serving under the command of NATO-led ISAF forces in Afghanistan. The US government has planned to send 21,000 additional combat troops and military advisers to the country before August's presidential election.(dpa)