Former world sprint champion has also had results dating back to July 15, 2012, annulled

American sprinter Tyson Gay has been banned for a year following his positive test for a banned substance.

The US Anti-Doping Agency (USADA) announced the suspension on Friday, confirming that the former world sprint champion had accepted the one-year ban for his anti-doping rule violation, as well as a loss of results dating back to July 15, 2012.

Gay is said to have already returned the Olympic silver medal he won as part of the US 4x100m relay team at the London 2012 Games.

The 31-year-old's suspension has been backdated to June 23, 2013 - the day his sample was collected at the USA Outdoor Track & Field Championships - meaning he will be eligible to return to competition next month.

Gay could have received a two-year ban, but he was eligible for a reduction having provided "substantial assistance" to USADA, a statement from the anti-doping agency advised.

"We appreciate Tyson doing the right thing by immediately withdrawing from competition once he was notified, accepting responsibility for his decisions, and fully and truthfully cooperating with us in our ongoing investigation into the circumstances surrounding his case," said USADA CEO Travis T. Tygart.

The statement confirmed that Gay tested positive for the presence of an "exogenous androgenic anabolic steroid and/or its metabolites".

The sprinter's sanction is subject to appeal by the IAAF and by the World Anti-Doping Agency.