Former German foreign intelligence chief August Hanning has been detained on suspicion of espionage, treason and obtaining classified information for a foreign power, Bild newspaper reported on Tuesday.
The report said prosecutors allege Hanning, whose tenure ended in 2005, bought secret information from a former employee of the foreign intelligence agency BND and intended to sell it on as part of his consulting activities.
The BND and the office of Germany's federal prosecutor did not immediately respond to Reuters requests for comment.
The investigation was launched after the discovery of an alleged leak of intelligence reports intended for the chancellery, Bild said.
This is a developing story.