Athletics faces crisis - IAAF president Lamine Diack

The man in charge of world athletics, IAAF president Lamine Diack, tells BBC sports editor Dan Roan that the sport faces a "crisis" in the wake of recent doping allegations.

The boss of the International Association of Athletics Federations says claims of widespread doping among Russian athletes aired in a German TV documentary, are "shocking" and "disturbing" but says the world governing body has not been involved in a cover-up.

Diack dismisses the allegation that as many as 99% of Russian athletes are guilty of doping as "a joke", and says he is "convinced that the majority of athletes are clean".