“It is not clear who the kidnappers are but we are looking for them,” he said.
“This the work of the Taliban,” he said.
“We are trying to establish contacts with our men in Wardak. At this stage it is not clear if our men are behind it,” he said.
Adrian Edwards, a UN spokesman in Kabul, said the Germans’ employers were unkown.
“We don’t have any idea who they are working for,” he said.
A German and his Afghan translator were kidnapped in southwestern Afghanistan in June and released after a week.
The Taliban issued Berlin with an ultimatum in March to withdraw its troops from Afghanistan.
General Aqa Nur Kyndoz, a police chief, said that the explosives were detonated outside the provincial police headquarters in Faizabad, the capital of Badakhshan province.
“One civilian was martyred and 27 others were wounded in the suicide attack,” he said.
“Eight of the wounded are reported to be in critical condition.”
Kyndoz blamed the attack on “enemies of peace,” a term often used by Afghan officials, referring to Taliban fighters.
Northern Afghanistan has been relatively peaceful compared to the south and southeast, where Taliban attacks happen almost daily.
Nato forces said that they were “not directly involved” and had no soldiers near the blast site.