KABUL: A NATO airstrike targeting insurgents inadvertently hit two civilian homes in the volatile southwestern Helmand province, killing 12 children and two women, an Afghan government official said Sunday. Dawood Ahmadi, a spokesman for the provincial government, said the alliance launched the airstrike late Saturday in retaliation for an attack earlier in the day on a US Marine base in Helmand's northwest district of Nawzad. He said NATO hit two civilian houses, killing five girls, seven boys and two women. NATO spokesman Maj. Tim James said a joint coalition and Afghan delegation was traveling Sunday to the site to investigate. He didn't confirm the airstrike and provided no details about it or the attack on the Marines. Civilian deaths are a constant source of tension between NATO and Afghan officials. President Karzai blamed American troops for airstrikes that killed the 14 women and children and two men, injuring of six other civilians. Afghan President Hamid Karzai has repeatedly called on coalition forces to minimize night raids and airstrikes and clear the operations with his forces. “We have told the Americans and NATO forces several times that uncoordinated operations will result in the killing of innocent civilians and that such operations are inhumane, but still no one has listened,” Karzai said Sunday. On Saturday, a Taliban suicide bomber wearing a police uniform blew himself up inside a heavily guarded compound in northern Afghanistan as top Afghan and international officials were leaving a meeting. The blast killed two senior Afghan police commanders and wounded a German general in command of coalition troops in the region.