A NATO air strike killed up to 33 Afghan civilians, including women and a child, sparking fresh anger from Kabul Monday against US-led forces pressing a major offensive to defeat the Taliban. Top US commander Stanley McChrystal, who has made winning Afghan hearts and minds the focus of plans to end the eight-year war in Afghanistan, was forced into another apology over civilian deaths after the third incident in a week. “We are extremely saddened by the tragic loss of innocent lives. I have made it clear to our forces that we are here to protect the Afghan people, and inadvertently killing or injuring civilians undermines their trust and confidence in our mission. We will re-double our efforts to regain that trust,” McChrystal said. McChrystal spoke to Karzai Sunday, expressing his “sorrow and regret for the tragic incident” and pledging to fully partner with the joint investigation, NATO said in a statement. McChrystal and his superior, General David Petraeus, mapped out an offensive lasting 12-18 months that would strike beyond the current focus of operations in the southern province of Helmand. But the third mistaken NATO air strike reported by Afghan officials in a week risked undermining the campaign's strategic goals. The government said four women and a child were among the civilians killed in Gujran district, Daykundi province, on Sunday when NATO forces mistook their convoy for Taliban militants. The air raid, which also injured 12 people, came days after a NATO rocket attack on a house killed at least nine Afghans.