Hoffenheim has alerted police to a drone allegedly flown by a Werder Bremen scout over its final training session before the teams' 1-1 draw in the Bundesliga on Wednesday.

The flying of drones over gatherings of people is forbidden in Germany, and Hoffenheim club spokesman Holger Kliem tells news agency dpa that the police has already begun its investigation.

Bremen sporting director Frank Baumann said after the game that a club scout was at Hoffenheim's training center but "anything that is illegal is unacceptable. We will speak about it internally first."

Hoffenheim midfielder Nico Schulz joked that he trained much better once he noticed the drone was there.