The groom and 17 of the guests at a rural Kandahar wedding party attacked by a suicide bomber on Wednesday were members of an anti-Taliban guard organisation encouraged initially by American Special Operations forces, and the bomber's goal appeared to be to undermine support for the group, elders and government officials in the area said.
The governor of Kandahar Province denounced the attack at a news conference.
"People from all walks of life are participating in a wedding: they are teachers, they are farmers, they are scholars, they are children," said the governor, Tooryalai Wesa.
"It's not legal to kill large numbers of innocent people," he said.
Forty wedding guests were killed and 87 were wounded.
The commander of the group, known as an arbeki, a traditional form of a village defence force, said the American forces had supported him at the beginning but then had backed away and never delivered ammunition or other promised support. His force is homegrown and home-financed, said the commander, Mohammed Nabi Kako.
Despite the bombing, in which 12 of his men died, Kako spoke confidently of his ability to hearten his forces and repel future insurgent attacks.