The German central command confirmed Friday's friendly fire incident, but put the number of Afghan casualties at five. The deaths occurred amid heavy fighting between German troops and militants near the northern city Kunduz.
The German military said German soldiers who were rushing from Kunduz to the scene of the fighting on Friday afternoon encountered two civilian vehicles and demanded that they stop. When they did not, a German armored personnel carrier opened fire on them, the statement said. The vehicles were later found to have been transporting Afghan troops and an investigation is pending, the military added.
Shortly before, German troops had been attacked while on a bridge-building and mine-clearing mission southwest of Kunduz city, formerly a relatively calm area in the north that has lately seen a rising level of insurgent violence.
Kunduz provincial government spokesman Muhboballuh Sayedi said Afghan commanders were meeting on Saturday with coalition forces to discuss the incident.
The Afghan Defense Ministry issued a statement condemning the incident and expressing condolences to families of the dead soldiers.
Kunduz is one of the principal bases for the 4,300 German troops currently deployed in Afghanistan. The German parliament recently approved the deployment of 850 reinforcements.
The German presence has been controversial, particularly since a German-ordered airstrike last September on two tanker trucks that had been captured by the Taliban in Kunduz killed up to 142 people.
Growing Taliban influence in Kunduz has threatened a key military supply line that opened last year following painstakingly negotiations between neighboring counties and the United States.
The land route via Russia and Central Asia offers an alternative means of providing essential supplies to the 120,000-strong NATO force in Afghanistan. Most supplies come in overland from Pakistan along a corridor that has been frequently attacked by militants.