The World Anti-Doping Agency is dismissing Australian sports scientist Stephen Dank's claim he had its permission to use a banned substance.
The body has released what it says is a series of email exchanges with Dank regarding the anti-obesity drug AOD-9604.
Reports said Dank had claimed he had an email from WADA, giving him permission last year to use the drug.
Dank said the email dated back to January last year.
But WADA issued a statement last week saying the drug is a banned substance.
The drug has become a hot topic as the Australian Sports Anti-Doping Authority continues its investigation into supplement use last year at Essendon AFL club where Dank used to work.
Dank also queried about a number of other supplements, asking whether they were permissible for use.