Mr. Karzai's increasingly bitter criticism of U.S.-led forces in Afghanistan threatens a complete breakdown in the crucial relationship between the Afghan government and Washington. Mr. Karzai said the Afghans would lose trust in international forces as a result of civilian casualties, more of which were "unacceptable."
Mr. Karzai's comments came despite his speaking to President Obama in an hourlong video teleconference Wednesday, the day the boys were killed in northeast Afghanistan. Mr. Obama "expressed his deep regret," the White House said.
The U.S. plan for Afghanistan depends on gradually transferring responsibility for security and governance to the Afghan government, and that requires cooperation that is imperiled by civilian casualties and other disputes.
Gen. David Petraeus met with Mr. Karzai Sunday and apologized for the incident in Kunar Province, in which nine boys -- said to be 7 to 13 years old -- were attacked by coalition helicopters.
"The apology is not enough," Mr. Karzai said in a statement. "Civilian casualties produced by the military operations of coalition forces are the cause of tension in relations between Afghanistan and the United States of America. The people of Afghanistan are fed up from these brutal incidents and apologies and condemnation cannot cure their pain."
The dispute was inflamed further when General Petraeus suggested in a meeting with Mr. Karzai that some civilian casualties were caused deliberately by Afghan parents to tarnish the coalition, referring to a separate incident in Kunar last month in which locals and Afghan officials claim 65 people were killed. Coalition forces insist that only insurgents died.
In response to the deaths of the boys, General Petraeus instructed all field commanders and helicopter crews to again study their rules of engagement.
The killing of the nine boys took place Tuesday in the Pech valley area of Kunar Province in eastern Afghanistan.
Lt. Gen. David Rodriguez, who directs day-to-day operations of coalition forces across Afghanistan, issued a video statement of apology.
In the video, General Rodriguez said troops at a base in the valley were responding to a rocket attack and dispatched attack helicopters to the location they were told the rockets came from. He said the helicopters thought they were engaging insurgents, but it later turned out they were boys from a nearby village who were cutting firewood.
According to a U.N. study, three-quarters of civilian casualties in Afghanistan are being caused by the Taliban. Some are deliberate in attacks on nonmilitary targets such as banks, shopping malls, and sports events. Sunday, a roadside bomb in the eastern province of Paktika, assumed to be planted by the insurgents, killed up to 12 civilians, including five children.
In Kabul Sunday, there was a demonstration in which several hundred people from a left-wing political party protested civilian casualties and demanded the withdrawal American government. They also burned an effigy of Mr. Obama.34.53091 69.13675
Response threatens fragile alliance between U.S., Afghanistan.