NATO officials in Afghanistan are investigating the latest deaths of civilians caused by an air strike and a clash with insurgents in the southern as well as eastern parts of the country. The probe comes as the U.S commander of foreign forces in Afghanistan has assured a traditional assembly of Afghan leaders his troops are making utmost efforts to avoid civilian casualties in what he described as "a difficult war".

NATO says its forces carried out an air strike Monday night on a compound in the district of Nahr-e-Saraj in southern Helmand province after coming under fire from insurgents hiding inside. NATO officials say four civilians, including two women and a child died in the airstrike.

It says the troops came to know about the presence of civilians, only after they entered the compound. NATO says that bodies of four suspected male insurgents were also found inside.

The second incident occurred in the eastern Kapisa province where a clash between NATO troops and Taliban insurgents wounded four children. One of the children died of wounds.

Both incidents are being investigated to determine whether NATO forces killed civilians.

Addressing a big gathering of tribal elders, religious scholars and political leaders from across Afghanistan in Kabul Tuesday, General Stanley McChrystal, commander of U.S. and NATO forces in the country, acknowledged his forces sometimes make mistakes and bring harm to civilians.

AP

US and NATO Forces in Afghanistan Commander Gen. Stanley McChrystal (File)

"When such unfortunate events occur we quickly investigate what happened and we admit our mistakes. While we strive to never bring harm to any civilian this is a difficult war," said McChrystal. "But the insurgents who place improvised explosive devices on your roads, who fire rockets into your neighborhoods, who use your women and children as human shields, they demonstrate everyday their disrespect for human life and never take responsibility or apologize for their actions," he said.

Last year, General McChrystal issued strict guidelines to limit air strikes against militants to avoid civilian casualties. But in Tuesday's address to the political gathering in the Afghan capital, the American commander said that too many local and coalition forces have also lost their lives or have been badly wounded while defending Afghans against suicide and other terrorist attacks.

"We are humans like you. We struggle here with you far from our homes and our families sharing your concerns about the challenges facing your communities," he explained. "We are proud to have paid in our blood as you have paid in yours to protect you from those who threaten Afghan security and to rob your children of a better future. We share this responsibility with you and feel the pain it comes with any loss of innocent life," said McChrystal.

The issue of civilian casualties in the fight against Taliban insurgents has been a source of tension between the Afghan government and NATO-led international forces. The latest such incidents have taken place amid a war of words between President Hamid Karzai and U.S officials. Critics say that the political tension could undermine international efforts to defeat the Taliban insurgency in Afghanistan.

The Afghan president in a recent speech to lawmakers is reported to have threatened to join the Taliban if foreigners do not stop meddling in Afghanistan.

Washington has described Mr. Karzai's comments as troubling and has urged him to carefully choose his words. The State Department spokesman has warned such comments could undercut U.S support for the Afghan mission.

President Karzai in his statement also accused the United Nations and international community of perpetrating election fraud in last year's presidential polls to try to tarnish his victory. U.N and U.S officials have rejected the charges, which many believe are meant to blame outsiders for Afghanistan's internal troubles, including growing corruption in the government departments.