Researchers have claimed that a study carried out at the University of Freiburg shows the presence of doping at now-Bundesliga clubs Stuttgart and Freiburg in the 1970s and 80s.
A research programme into historical doping allegations shows, according to the university's Evakuierungskommission Freiburger Sportmedizin, there was "systematic misuse of steroids in German professional football".
As well as the German Association of Cyclers, Stuttgart and Freiburg were both implicated, although both clubs say they are yet to receive the full contents of the report.
Freiburg said in a statement they were "only in hand of the two documents having been published - one press release and one abstract" and that they had not seen "detailed results of determination or expert’s reports".
Similarly, Stuttgart said: "VfB Stuttgart is not in hand of the mentioned report.
"The club therefore can't retrace the evidence basing the accusation or know if and to which point they are true."