Godolphin racing manager Simon Crisford has said he is "shocked", after 11 horses from the Godolphin stable tested positive for anabolic steroids.
Mr Crisford said: "This is a dark day for Godolphin. We are all shocked by what has happened".
"His Highness Sheikh Mohammed was absolutely appalled when he was told and this is completely unacceptable to him. We will await the outcome of the BHA inquiry before taking any further internal action", added Mr Crisford.
"Sheikh Mohammed has instructed me to begin an urgent review of all of our procedures and controls. That is already under way and we will take advice from the BHA in completing it."