The bombing happened at 1.00 a.m. on Monday in a rugged region, residents told the local Pashtu service of the BBC.

"There was no-one to help last night," resident Abdul Saboor told the BBC. "We managed to transfer some of the wounded to Kandahar in the morning. Some of the foreigners' choppers also came to see who they had killed and laugh about it..

"There are no Taliban or al Qaeda or Arabs here. These people were all civilians, women and children."

The International Security Assistance Force, responsible for security in the capital Kabul, 170 miles to the north, told Reuters it had contacted the U.S. liaison office which had heard nothing of any attack.