German Economy Minister Robert Habeck's constituency office in northern Germany said on Thursday that it had received an envelope containing a white substance, prompting a large-scale police operation.
Employees of the office in Flensburg, near the border with Denmark, brought the envelope to police at 3:50 p.m., who subsequently alerted the fire brigade, police said in a statement issued late Wednesday.
The police operation lasted two hours, and the white substance was subsequently removed from the building by the fire brigade in a container.
Police said that no damage had been caused and no one's health had been impacted.
"An analysis of the powder has been initiated - the result is still pending," police said in the statement.
Flensburg police could not be reached for further comment.