ASADABAD, Afghanistan (Reuters) -- A blast near a U.S. troop convoy in Afghanistan has killed at least one child and wounded 34 civilians, officials said, but witnesses blamed a U.S. soldier for throwing a grenade into a crowd.
Abdul Jalal Jalal, chief of police in Kunar Province, said officials were investigating whether the blast in the provincial capital, Asadabad, was caused by a grenade thrown by U.S. troops or by an insurgent attack.
A U.S. military spokesman in Kabul said he was checking the reports.
Several of the wounded and other witnesses told Reuters a U.S. soldier had thrown a grenade after the military convoy was stopped because a vehicle's tire had burst.
Civilian casualties caused by U.S. forces have become a major source of friction between the Afghan authorities and their U.S. allies, and have hurt public support even as the number of U.S. troops in the country more than doubles this year.
"I was on my way to school. Their tire burst, and then a soldier hurled a hand grenade from the convoy," said Abdul Wahab, 12, lying in a hospital bed with two shrapnel wounds in his leg.
Two other wounded victims at the Asadabad hospital gave similar accounts.
A 20-year-old shopkeeper near the scene, Umranullah, who uses only one name like many Afghans, also said a U.S. soldier from the convoy had thrown a grenade.
Asadabad hospital doctor Ehsanullah Fazli said most of the wounded were children.
The Pentagon acknowledged on June 8 that procedures had been violated during an air strike last month in which the Afghan government says 140 civilians were killed.
Washington says 20-35 civilians were among 80-95 people killed, most of them Taliban fighters, in the air strike in western Farah Province.
Fearing strikes by suicide bombers and other attacks by Taliban, foreign troops in the past have fired at Afghan civilians, causing casualties.