A US military spokesman in Bagram said the rebels were killed by two AH-64 Apache gunships after a group of 15 opened fire on a coalition special forces patrol from a ridgeline north of the town of Kandahar on Thursday.
"The remaining enemy fighters retreated to nearby caves," Lieutenant Colonel Douglas Lefforge told a news briefing.
In another incident in the southern part of Kandahar province close to the border with Pakistan on Thursday night, a coalition special forces team came under small-arms fire from three rebels near their base at Spin Boldak, Lefforge said.
"The team pursued the enemy fighters, but the pursuit ended when the enemy fighters crossed the border into Pakistan," he said.
Lefforge said there were no coalition casualties in either incident.
"The team pursued the enemy fighters, but the pursuit ended when the enemy fighters crossed the border into Pakistan"
US military spokesman
He could not say whether the fighters were loyal to the former Taliban regime, the allied al-Qaida network or to the Islamist commander Gulbuddin Hekmatyar, all of whom have been blamed for past attacks on United States-led troops.
About 12,500 US-led foreign troops are in Afghanistan pursuing Taliban remnants and fighters of the al-Qaida network of Usama bin Ladin.