alt Isabell Werth's offer to resign from the International Dressage Riders Club (IDRC) has been refused despite her being under suspicion after one of her horses tested positive for banned drugs.


The five-time Olympic dressage champion has become the latest top Germany to be suspended by her national federation following a positive doping test to her horse, Whisper, at an event on May 30.


She claims a veterinarian-recommended treatment given to her horse to alleviate the symptoms of Shivers contained a banned substance.


Margit Otto-Crepin, the President of the IDRC, confirmed that the IDRC board members received an email from Isabell Werth earlier this month informing the committee of her intention to resign as member and board member of the IDRC, a group that represents the interests of all dressage riders particularly those taking part in FEI international competitions.


But, in an open letter, Otto-Crepin refused her resignation.


She wrote: "While we understand and appreciate your concern that the IDRC will be negatively affected by the fact that you are subject to an ongoing investigation by the FEI for use of a banned substance, we wish to advise you that we cannot accept your resignation.


"We have complete faith that you will be vindicated and cleared of any intentional wrongdoing.


"We wish to offer you our wholehearted support and look forward to your continued participation in our activities."