The suicide attack on Sunday targeted a personnel carrier of the German armed forces stationed in the city of Kunduz in northern Afghanistan.
The commander of the German military outpost in Kunduz, Colonel Norbert Sabrautzki, was traveling with the convoy. He escaped the attack unharmed.
"A suicide bomber detonated explosives targeting a vehicle that carried German soldiers on the Kabul-Kunduz highway outside Kunduz city," said government spokesman Mahbubullah Sahidi.
He added that the German vehicle was destroyed in the blast, but that there was no news on German casualties.
However, at least two Afghan civilians were killed and several others injured.
An explosives-laden vehicle driven by the attacker detonated as the military convoy was passing by in the Chahar Saraka area of Kunduz, the Interior Ministry said.
Taliban spokesman Zabiullah Mujahid took responsibility for the attack, saying a fighter drove a vehicle packed with 550 kilograms of explosives into the convoy and killed 12 NATO soldiers.
However, NATO denied the casualty claim.
"Our initial reports say a NATO vehicle carrying soldiers was hit by an improvised explosive device, but there are no reports of casualties on the NATO side," said NATO spokesman, Major Tim James.
Germany has a significant presence in the Kunduz region of northern Afghanistan, which has seen a growing number of attacks in recent weeks since the killing of al Qaeda leader Osama bin Laden by US special forces in early May.
Two Germans were killed last month in an attack which also killed a regional police chief.
The commander of NATO forces for northern Afghanistan, German General Markus Kneip, survived the attack with minor injuries.
Author: Gregg Benzow, Spencer Kimball (dpa, AFP, Reuters)
Editor: Mark Rossman