Officials said on Wednesday that the camp in Uruzgan province had been used as a base by about 80 fighters to launch guerrilla-style assaults on Afghan and US-led coalition forces in the area.
The rest of the rebels fled during Tuesday's attack on the camp, which had been set up in several adjoining mountain caves, provincial Governor Jan Mohammed Khan said.
American helicopters pounded the site with rockets before ground forces moved in. Several AK-47 assault rifles, rockets, as well as tents, kettles and other camping equipment were scattered around the area, the governor said.
The bodies of the eight killed were discovered, he said.
Coalition and Afghan forces have launched an offensive against the anti-government Taliban in the lead-up to legislative elections on 18 September.
US and local officials have said they fear the fighters are intent on subverting the polls and have warned that a major upsurge in violence in recent months may further worsen in the next few weeks.
But Nato's top commander played down the threat on Tuesday, saying the upsurge in violence came from a desperate group of fanatics and criminals and does not present a major threat to the country's stability before next month's election.
"This is not a coordinated threat that we think could lead to any greater degree of insurrection," said General James Jones.
Nato has strengthened its role in
the run-up to September's vote
He spoke at a news conference in the Afghan capital, Kabul, during a two-day visit to Afghanistan to assess Nato's strengthened security role ahead of the 18 September vote.
Jones said reinforcements, which have taken the Nato force to 11,000, backed up with increased air power, should be sufficient to guarantee security in Kabul and the northern and western regions, which are under Nato's security
He also expressed confidence that Afghanistan was not in danger of falling into Iraq-style violence.