Germany's public prosecutor’s office said it was investigating Vodafone’s chief executive and Deutsche Bank management board member Mr Josef Ackermann over irregularities in Vodafone's takeover of Mannesmann, concluded last year.
The prosecutor based in the city of Duesseldorf said that the probe also targeted former Mannesmann chief executive Mr Klaus Esser and IG Metall trade union head Klaus Zwickel, among others.
Deutsche Bank declined to comment.