Tennis super-star Rafael Nadal has said he has nothing to hide after his medical record was leaked by cyber-hacking group "Fancy Bears".

The Spanish player said he had asked for permission to use the otherwise-prohibited drugs, to cure his troublesome knee. Records show Nadal has been granted therapeutic use exemption, or TUE, twice by the World Anti-Doping Agency.

Nadal insists that he was simply following the advice of his doctors and that this is nothing new. Nadal is among more than 60 international athletes, whose medical files were publicly published online by the hacking group.