Godolphin trainer Mahmood Al Zarooni could lose his training licence when he faces a disciplinary panel of the British Horseracing Authority tomorrow.
Yesterday, he admitted making "a catastrophic mistake" after 11 of his horses were found to have contained traces of anabolic steroids.
The 37-year-old has officially been charged with rule breaches related to prohibited substances, duty to keep medication records, and conduct prejudicial to racing.
The hearing will be held at 2.30pm at BHA headquarters in London.
Godolphin trainer Mahmood Al Zarooni will stand before a disciplinary panel of the British Horseracing Authority on Thursday afternoon after samples taken from 11 of his horses were found to have contained traces of anabolic steroids.
Dubai-owned horse racing giant Godolphin, one of the wealthiest and most powerful operations in the sport, has been rocked to its foundations by allegations of doping.
Bookmakers have refunded hundreds of thousands of pounds worth of bets after it emerged 11 horses at the Godolphin stables at Newmarket had tested positive for steroids.
ITV News' Correspondent Richard Pallot reports.
Bookmakers Ladbrokes said it has taken the decision to return £200,000 worth of bets after horses trained by Godolphin's Mahmood Al Zarooni tested positive for steroids. Alex Donohue of Ladbrokes said:
Certify was one of the most popular ante post horses of the season. She was the big race favourite all winter but given the circumstances we feel it's only fair customers get their money back.
Bookmakers Ladbrokes has said it will be refunding money on certain bets after it was revealed that 11 horses tested positive for steroids in the care of Godolphin trainer Mahmood Al Zarooni.
Our own @magicsignman has revealed here at Ladbrokes "We have refunded £200,000 alone on Certify".
ALL bets on Certify, Desert Blossom, Artigiano and Restraint of Trade will be voided. Money will be back in your accounts shortly.
The National Trainers Federation has said it is "shocked" by the news of positive tests on horses trained by Godolphin's Mahmood Al Zarooni.
In a statement, the NTF chief executive Rupert Arnold said: "Like everyone else in the sport of horseracing, the NTF is shocked at the news of these positive tests at the stable of Mahmood Al Zarooni.
"News reports so far suggest this case is an aberration and is not indicative of wider use of anabolic steroids in British horseracing.
"Without wanting to diminish the seriousness of this case, in some ways it is a positive message that the presence of these substances was detected so the sport is kept clean."
A prestigious horseracing series has said the British Horseracing Authority's (BHA) decision to suspend Godolphin trainer Mahmood Al Zarooni shows that the substance testing programme "works".
Qipco British Championships wrote on their website, after 11 horses including unbeaten filly, Certify tested positive for steroids, and subsequently will not be racing on Saturday.
They said: "It is a bad day for racing, but on the plus side it shows that the BHA testing programme works and that trainers cannot expect to get away with the use of performance-enhancing substances".
Horse racing commentator Derek Thompson says he was stunned when he heard the news that 11 horses at the Godolphin stables in Newmarket were tied up in a doping scandal.
He said: "This news is stunning. Eleven horses tested positive, not one or two who might have been ill. That is not good news."
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Horses that tested positive for anabolic steroids have been suspended with "immediate effect and for an extended period of time", the British Horseracing Authority (BHA) said today.
Samples taken from 11 horses in Godolphin trainer Mahmood Al Zarooni's care were found to contain traces of the substance. Adam Brickell, Director of Integrity, Legal and Risk for the BHA, said:
Ethylestranol and stanozolol are anabolic steroids and therefore Prohibited Substances under British Rules of Racing, at any time - either in training or racing. Mahmood Al Zarooni has been advised of the analysts' findings and has been visited by an Investigating Officer.
As part of the ongoing process a decision will be made as to what period this suspension will be imposed for.
The BHA understand the importance of this process being carried out as quickly as possible because of implications for betting markets.