Trainer Gerard Butler is set to face charges over his over his use of the drug Sungate, which contains a banned anabolic steroid.

The Newmarket trainer admitted to being subject to a British Horseracing Association investigation concerning the joint treatment, which was developed by an Italian company and contains stanozolol.

While it is legal to use the drug in Britain when it is imported under licence, the active ingredient is a prohibited substance in racing.

Butler admitted in a newspaper interview he used the substance on several horses in his stable after receiving assurances from a veterinary practice, and he entered this into his official medical records.

"The BHA can confirm it is likely that charges will be brought against Gerard Butler within the next few days," a statement from the BHA said.

"Further to our update on May 17, the wider investigation into the use of Sungate in other yards continues.

"The BHA is currently gathering all relevant information in order to establish the extent of the use of the product, which has included interviews with several trainers.

"This information will determine how we will proceed with this investigation."

In April, Godolphin trainer Mahmood Al Zarooni was disqualified for eight years for using banned anabolic steroids on horses in his stable.