( CNN ) -- The ruler of Dubai 's prestigious Godolphin operation in Britain is at the center of a major doping scandal after 11 of the stable 's horses failed drugs tests . Godolphin said Sheikh Mohammed bin Rashid Al Maktoum was `` absolutely appalled '' after regulator British Horseracing Authority ( BHA ) found anabolic steroids -- ethylestranol and stanozolol -- in 11 samples taken from 45 horses from its Newmarket stable in eastern England on April 9 . `` I deeply regret what has happened , '' said Godolphin trainer Mahmood Al Zarooni , who now faces a BHA disciplinary inquiry , in a statement by Godolphin . `` I have made a catastrophic error . Because the horses involved were not racing at the time , I did not realize that what I was doing was in breach of the rules of racing . `` I can only apologize for the damage this will cause to Godolphin and to racing generally . '' Anabolic steroids work on horses as they do on humans -- helping to build strength and muscle . Stanozolol was still legal as recently as 2008 , when Big Brown won the Kentucky Derby and the Preakness Stakes in the U.S. after having regular injections . His trainer 's admission , and the subsequent outcry , led to the drug being widely banned . However , it is still legal for out-of-competition use in Australia , such as helping to overcome injuries . ''Any horse that has been treated with anabolic steroids must be free of them by race day , '' Racing Victoria vet Dr Brian Stewart told the Sydney Morning Herald on Tuesday in reaction to Monday 's Godolphin announcement . Godolphin is one of the world 's most successful stables , with more than 2,000 race wins since it was formed in 1992 . It has been named Champion British Owner eight times , including last year , while Sheikh Mohammed and his family have also taken the title on multiple occasions going back to the 1980s . Godolphin 's Certify , unbeaten in four career outings and winner of the Shadwell Stud Fillies ' Mile at Newmarket last September , was one of the horses to test positive and will not be allowed to take part in the 1,000 Guineas at Newmarket next month . `` Mahmood Al Zarooni has been advised of the analysts ' findings and has been visited by an investigating officer , '' said Adam Brickell , Director of Integrity , Legal and Risk for the BHA . Former Dubai Gold Cup winner Opinion Poll was another horse to test positive . Opinion Poll was ridden to victory in that race by Frankie Dettori , who worked for the Godolphin team for 18 years , but is now serving a six-month ban for doping . Urgent review . `` This is a dark day for Godolphin , '' said the British stable 's racing manager Simon Crisford . `` 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 . `` Sheikh Mohammed has instructed me to begin an urgent review of all of our procedures and controls . That is already underway and we will take advice from the BHA in completing it . '' The BHA said the disciplinary hearing will take place at the `` first available opportunity . '' `` Ethylestranol and stanozolol are anabolic steroids and therefore prohibited substances under British Rules of Racing , at any time -- either in training or racing , '' added Brickell , outlining the sport 's doping rules on the BHA 's website . `` The horses which have produced positive tests will also not be permitted to race with immediate effect and for an extended period of time . `` As part of the ongoing process , a decision will be made as to what period this suspension will be imposed for . `` The BHA understands the importance of this process being carried out as quickly as possible because of implications for betting markets . '' Zarooni joined Godolphin in March 2010 and won the St. Leger , one of Britain 's five classics , in his first season . `` News reports so far suggest this case is an aberration and is not indicative of wider use of anabolic steroids in British horse racing , '' said National Trainers ' Federation chief executive Rupert Arnold .
A total of 45 horses at prestigious stable Mahmood Al Zarooni fail drugs tests . Trainer Godolphin says he is responsible for administering banned steroids . Highly-rated filly The British Horse Racing Association and Opinion Poll are among horses to test positive . Certify summon trainer to attend disciplinary hearing .