The killings were the latest in a campaign of attacks by the extremists who target Afghan and foreign soldiers, as well civilians who work for them in a spiralling insurgency that has killed thousands of people.
A group of 10 workers had left the American military base in the eastern province of Kunar in a minibus late on Thursday when they were stopped by gunmen, provincial police chief Abduljalal Jalal told AFP.
"The gunmen sprayed the vehicle with bullets," he said. Two labourers managed to escape.
"Eight labourers were brutally shot and killed by armed men in Korangal area. They were working at a US base and were going home for Eid holidays," Jalal said.
No one claimed responsibility for the attack but Jalal blamed extremist Taliban guerrillas who are waging an insurgency that has intensified every year since a US-led coalition removed them from government in late 2001.
The deputy police chief, Abdul Saboor, said the men were attacked in a valley in the late afternoon by up to 25 men who had their faces covered.
"According to the information we have, 350,000 afghanis (7,000 dollars) was also stolen from them," Saboor said.
Saboor also said he believed the attackers were Taliban. "I think this is the work of the enemies of Afghanistan because thieves do not dare to kill eight people together for money," he told AFP.
The term "enemies of Afghanistan" is used by Afghan officials to refer to the Taliban. "They were killed for working for Americans."
About 250 people gathered in the Kunar capital Asadabad on Friday to protest the killing, Saboor said. Reports said the protestors chanted slogans against the Taliban and al Qaeda.
The Taliban were also likely to have been behind a suicide bombing near the eastern city of Khost Friday in which a soldier was killed and 10 other people hurt.
The attacker waited for an Afghan army convoy that had to slow down at a speed bump and then detonated explosives strapped to his body, the provincial police chief General Mohammad Ayoob said.
"One soldier was martyred and other seven were wounded in the suicide attack," army general Mohammad Akram Sami told AFP. Three civilians were also seriously injured in the blast, the police chief said.
Khost has suffered several suicide blasts in the past weeks. One on Thursday killed a policeman and wounded five others.
The US-led coalition said it had killed a "terrorist" and captured four others in a raid early Friday on a compound in Khost province where improvised bombs were being made.
"During the search of the compound, multiple blasting caps, detonation cord and explosives were found," the force said in a statement.
The raid was launched after "credible information" that there was a cell working on improvised bombs operating around Khost city, it said.
There has been a dramatic increase in the number of suicide attacks in Afghanistan this year, the bloodiest since the Taliban launched its insurgency soon after being forced out of power.
The violence has claimed around 3,000 lives so far this year, with rebels accounting for most of the dead. This is about double last year's estimated toll.
A second suicide blast Thursday killed a British Royal Marine and two children in the volatile southern town of Lashkar Gah. Another Marine was injured and was in a stable condition Friday, NATO said.
In another attack reported Friday, police said a dozen Taliban attacked a district in eastern Paktika province late on Thursday. One militant was killed and five others wounded, police chief Abdul Baqi Nuristani told AFP.

Copyright AFP (Agence France-Presse), 2006