An Afghan senator in charge of an investigation into the bomb blast that left three Afghan civilians dead says US troops were behind the explosion.
Senator Saleh Mohammad made the remarks a day after an explosion among a crowd of people around a US military convoy in Kunar province left 58 civilians wounded.
"I went to the hospital, I spoke to the wounded, I went to the site and spoke to the witnesses and now can say that the bomb was not thrown by the opposition but it was thrown by American forces," he was quoted by AFP as saying.
However, the US military denied the allegation, releasing a video to prove its troops were not responsible for the blast.
The US military also issued a statement, claiming that the blast was caused by a Russian-made grenade, a type of grenade the US forces do not use.
The Afghan official, however, said he had seen the video but "couldn't believe it".
Afghans are outraged at repeated US air strikes which have so far killed hundreds of civilians.
Last month, an air raid by US forces killed 140 civilians in one of the deadliest attacks since foreign troops invaded Afghanistan in 2001.
Admitting its forces failed to follow procedures, the US claims that the toll was only 20-30 civilians.
An investigation is underway over the murder of Afghan civilians by US troops.