Newmarket racehorse trainer Mahmood Al Zarooni is appearing at the British Horseracing Authority headquarters to face a disciplinary hearing over doping.
Al Zarooni was surrounded by a media scrum as he entered the building in central London with Simon Crisford, spokesman for the Godolphin operation, but did not speak to waiting reporters.
The trainer was charged after tests on 11 of his horses showed the presence of anabolic steroids.
He could lose his licence as a result of the hearing, in what is one of the most significant doping scandals in recent racing history.
Racehorse trainer Mahmood Al Zarooni has been disqualified for eight years after 11 of his horses tested positive for anabolic steroids.
The Newmarket Godolphin stables are at the centre of horse doping allegations involving 11 horses and the trainer Mahmood Al Zarooni.