Local government spokesman Mubarez Zadran said a suicide car bomber struck the convoy as it rolled through Khost province's Mando Zayi district. He said foreign troops quickly cordoned off the road.
The international force confirmed the Khost explosion, but spokeswoman Lt. Cmdr. Katie Kendrick said the convoy apparently hit a roadside bomb. She said no casualties were reported.
Insurgents have intensified attacks across the country as 30,000 more American troops arrive to try to turn around the 9-year-old war against the Taleban and stabilize the Afghan government.
Attackers also targeted a southern Afghan army base Saturday morning, but the government said a would-be suicide bomber was shot dead and no soldiers were hurt. A Taleban spokesman claimed two bombers penetrated the base and killed more than a dozen Afghan and international forces.
Guards at the base gate in the Zabul province noticed a man approaching at about 7 a.m. and killed him, the Ministry of Defense said in a statement. It said the soldiers found the man was wearing a vest full of explosives and was carrying hand grenades and an AK-47 assault rifle.
Soon after, soldiers captured two other insurgents armed with another rifle and a rocket-propelled grenade launcher, the ministry said.
Taleban spokesman Qari Yousef Ahmadi, however, called reporters Saturday and claimed that two suicide bombers entered the base and successfully detonated their vests, killing 17 Afghan and foreign troops.
The insurgents often exaggerate the success of their attacks for propaganda purposes.