Details of the charges brought by the British Horseracing Authority against trainer Mahmood Al Zarooni, as well as the date of his hearing, are expected to be released on Wednesday.

It was announced on Monday that Al Zarooni is to face the BHA disciplinary panel after samples taken from 11 horses in his care in Newmarket were found to contain traces of anabolic steroids.

Samples were taken earlier this month from 45 horses trained by Al Zarooni at Moulton Paddocks Stables and subsequent analysis revealed 11 of the samples had present in them prohibited substances, namely ethylestranol and stanozolol.

Certify, unbeaten in four career outings and winner of the Shadwell Stud Fillies' Mile at Newmarket in September, was one of the seven horses whose sample tested positive for ethylestranol. She had been ante-post favourite through the winter months for the Guineas, and only recently lost that position to the Sir Henry Cecil-trained Hot Snap. Ascot Gold Cup runner-up Opinion Poll was one of four horses testing positive for stanozolol.

The BHA tweeted: "Full details of the charges being brought against Mahmood Al Zarooni and the date for the hearing will be published tomorrow morning." The National Trainers Federation has admitted it is "shocked" at the news of positive tests for steroids on horses trained by Al Zarooni.

The trainers’ professional body says it fully endorses the BHA’s regime of testing in training.

In a statement, 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.

"The Godolphin management, for whom Mr Al Zarooni trains, is a byword for the highest levels of professionalism, integrity and sportsmanship. "News reports so far suggest this case is an aberration and is not indicative of wider use of anabolic steroids in British horseracing. "We fully endorse the British Horseracing Authority's testing in training regime and all efforts to prevent the use of any prohibited substance to gain an unfair advantage.

“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.”

Al Zarooni, who won the Ladbrokes St Leger at Doncaster last year with Encke, as well as the richest race in the world, the Dubai World Cup, with Monterosso, has trained a whole host of big-race winners since joining Sheikh Mohammed's operation.

Al Zarooni admitted he had made a “catastrophic error” in using the banned substances, saying he did not realise he had broken the rules as the horses were not racing at that time.

Speaking to BBC Radio 5 Live, David Mountford, chief executive of the British Equine Veterinary Association, said: "The rules are fairly clear, and I think most trainers would be aware of those rules. The use of anabolic steroids in training is banned in UK racing. "It's obviously being taken very seriously by all concerned. And I would expect if, as looks likely, people are found guilty of breaching the rules, they would be treated severely."

Also speaking to BBC Radio 5 Live, Lincolnshire-based trainer James Given, who is a qualified vet, said: "The number of horses that tested positive shows that it wasn't what one might term an error with a single horse.

“It is, without doubt, a performance-enhancing drug. It’s not just active while the drug is in the body — and certainly many of these drugs will persist in the body for several months — but it’s the effect on the muscle development beyond its natural capacity.”