Security officials said it was unclear if the man whose bicycle exploded near an International Security Assistance Force (ISAF) convoy in the northern city of Kunduz was a suicide attacker, police commander Mohammad Razaq told AFP.

He may have been unaware his bike was rigged, Razaq said.

"A man riding a bicycle came near the ISAF car and the bicycle exploded," Razaq said. "The man and a bystander were killed, 12 local people were injured and one ISAF (soldier) was injured," he said.

German officials said they were investigating the incident, but didnt anticipate increasing security measures for the 2,500 soldiers taking part in the ISAF force. Since a bomb killed a German soldier last November, troops have already been put on a heightened state of alert.

Germany's parliament extended and expanded the Bundeswehr mandate in Afghanistan at the end of September. Five hundred additional soldiers will be deployed. Right now, there are 350 troops stationed in Kunduz.