Afghan President Hamid Karzai has condemned a NATO airstrike that reportedly killed seven civilians, mostly children, in southern Afghanistan.

Mr. Karzai's office said Thursday that reports by local officials indicate that an airstrike conducted by international forces in the Zheri district of Kandahar province killed seven people, including six children. Two young girls were wounded.

The Afghan president's office says Mr. Karzai was saddened when he heard the news and has designated a team to investigate the incident. NATO also has launched an investigation into Wednesday's incident.

The commander of U.S. and NATO forces in Afghanistan, U.S. General John Allen, said he also was saddened by the event and that protecting the Afghan civilian population is central to the coalition's mission in the country.

The governor of Zhari district, Niaz Mohammad Sarhadi, told the French news agency that the strike was aimed at Taliban fighters planting roadside mines but missed its target and hit nearby residential areas.

In a statement, NATO officials said they had identified and were responding to offensive actions by insurgents.

Civilian deaths have long strained the relationship between the international forces and Afghan government.

In western Afghanistan Thursday, Afghan officials say Taliban militants killed at least seven local guards in an attack on a convoy carrying goods for international forces.

A spokesman for the governor of Farah province said insurgents destroyed at least nine trucks in Thursday's raid. Afghan police arrived at the scene to intervene.

The Associated Press quoted the provincial spokesman as saying no foreign troops were involved in the attack.

While the Taliban did not immediate claim responsibility for the assault, attacks on NATO convoys have been a major tactic in the militant's 10-year-long insurgency.

The major land routes for NATO supplies to landlocked Afghanistan also go through Pakistan, where militants there frequently target the trucks.