Racehorse trainer Gerard Butler could face a ban from the sport for treating horses with the drug Sungate, which contains a banned anabolic steroid.

He has been charged by the British Horseracing Authority (BHA) and will face a disciplinary hearing.

Sungate is used to treat joint problems and is legal to use in Britain when it is imported with a licence. But the active ingredient — stanozolol — is banned in racing.

Stanozolol is one of the steroids that disgraced former Godolphin trainer Mahmood Al Zarooni’s horses tested positive for. He was banned for eight years last month.

Nine of Gerard Butler’s horses tested positive for the steroid when samples were taken on 20 February.

He faces charges of breaching six Rules of Racing and is charged with “acting in a manner prejudicial to the integrity, proper conduct and/or good reputation of horseracing”.

And he faces further charges relating to failing to keep a record of treatments and injecting joints himself. This is prohibited because he is not a qualified or registered vet.

The horses that tested positive are: A Touch Of Fashion, Flemish School, Azrag, La Belle Epoque, Rainbow Beauty, Zain Eagle, Zain Queen Zain Spirit and Prince Alzain.

In April, in the wake of the Al Zarooni scandal, Butler admitted using Sungate but said he didn’t know the drug breached the rules and that he’d been “advised in good faith” by vets. He added that he believed around 100 more horses in the Newmarket area had received similar treatment.

The BHA confirmed that a wider investigation into the use of the product Sungate remains ongoing. A spokesman said they have spoken to several trainers to establish the extent of the use of the product.