The U.S.-led coalition said three U.S. soldiers were killed and two others injured in clashes with Tablian militants in the northeastern province of Nuristan.
There was no mention of any Taliban casualties.
In a separate incident, officials said a Canadian NATO soldier was killed in a suicide car bomb attack in Kandahar Province, in the south of the country.
His death brings to seven the number of Canadian personnel killed in Afghanistan in the past week.
A purported spokesman for Taliban militants claimed responsibility for the attack.
In another incident, the U.S. military said U.S.-led and Afghan forces killed three suspected Al-Qaeda militants in a raid in the eastern province of Khost.
(compiled from agency reports)