A US military spokeswoman in Kabul, Lieutenant Tamara Lawrence, said several troops were wounded in the blast in the Khost province, close to the Pakistan border.
"We have very limited information, but there are no reports of coalition casualties, only reports of injured," she said.
The Pakistan-based Afghan Islamic Press news agency said a Taliban spokesman Mohammad Hanif had called to say the attack was carried out by one of their fighters.
Regular attacks are carried out on coalition troops in Afghanistan by Taliban forces trying to regain power after being removed from government in late 2001.
Soldier dies in base
A US soldier has died in Afghanistan, but hostile action is not suspected, the US military announced.
The soldier died on Monday at Forward Operating Base Salerno in the southeastern province of Paktika, the military said.
"The exact cause of death has yet to be determined; however, neither enemy action nor foul play is suspected," a statement said.
The soldier's identity has been withheld while relatives are told.