Blast near U.S. convoy wounds scores

ASADABAD, Afghanistan (Reuters) - A blast near a U.S. troop convoy in eastern Afghanistan killed at least one child and wounded scores of civilians on Tuesday, a provincial governor said.

The U.S. military said three U.S. soldiers and at least one Afghan child were hurt in the blast.

Some witnesses blamed a U.S. soldier for throwing a grenade into a crowd, however the U.S. military said a grenade had been thrown by an insurgent.

Kunar Province Governor Fazlullah Wahidi said 49 people were wounded. Provincial police chief Abdul Jalal Jalal 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.

U.S. military spokeswoman Captain Elizabeth Matthias said a convoy of U.S. troops had stopped when one of its armoured vehicles became stuck.

The convoy took ground fire and an insurgent threw a grenade, wounding three soldiers and a 12-year-old boy, she said. She said the military was checking reports other civilians were also hurt.

Several of the wounded and other witnesses told Reuters a U.S. soldier had thrown a grenade.

"I was on my way to school. Their tyre 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. Some were in critical condition, he said.

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.

The Pentagon acknowledged on Monday 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 that strike in western Farah province in early May.

(Additional reporting and writing by Sayed Salahuddin in KABUL; Editing by Peter Graff and Paul Tait)