The doping probe against runners Sofia and Sara Benfares has shocked the German athletics federation DLV which insisted it stands for clean sport.
Germany's Anti-Doping Agency (NADA) is probing the sisters after Sara Benfares tested positive for the blood booster EPO and the steroid testosterone, and Sofia Benfares for EPO at out of competition tests last year.
Legal proceedings have also started because doping is a criminal offence in Germany.
The DLV is not directly involved in the probe run by NADA, and its high performance sport board member Jörg Bügner told broadcasters ARD at the world indoor championships in Glasgow that they won't comment directly on the two cases.
But he said that "It goes without saying that this has hit us like a bomb. We are of course very concerned.
"And of course our strategy is still clear. We are 100% in favour of the fight against doping, for clean and fair sport. And of course that has also left deep marks on us, that has to be said quite clearly."
Bügner said there could never be 100% guarantee of clean sport, especially when "criminal energy" is involved, but he said the positive tests showed that the system is working, although he would favour even more tests.
Sara Benfaras' father and coach, Samir Benfares, told a French portal that the positive test was the result of medication she took after a bone cancer diagnosis.
The sisters grew up near Paris but compete for Germany where they have now been suspended by their club.
Sara Benfares came 12th over 5,000m at the 2022 European championships and was aiming to compete at this year's Paris Olympics. Her younger sister Sofia was third over 3,000m at last year's European junior championships.
