USADA announced Friday that the 31-year-old American track star tested positive for a banned anabolic steroid in two random out-of-competition tests and one event doping test in urine samples taken last year by both USADA and the world governing body IAAF.

Gay accepted a one-year period of ineligibility that began on June 23 of last year, the day his sample was collected at the US Outdoor Track and Field Championships.

Because the random test positives were collected near the date of the meet, they were treated as one violation.

While the suspension timing means that Gay can return to competition next month, he will do so too late to take part in Diamond League meets at New York or Eugene, Oregon, or qualify for the US Track and Field Championships at Sacramento, California, on June 26-29.

Gay accepted a one-year doping ban from last June and the disqualification of all results dating to July 15, 2012 — the date he first used a product that contained a banned substance — and forfeited all prizes obtained from that date, which included voiding his effort on the US Olympic men's 4x100m relay runner-up squad at London.

USADA said Gay has already handed over his silver medal to USOC officials.

Also thrown out was Gay's fourth-place showing from London in the 100m final in 9.80 seconds, what had been the fastest non-medal effort in Olympic history.

After learning of his violation last year, Gay went public and said that while he never knowingly or willfully took a banned substance, he had made a mistake but did not elaborate.

- Subject to appeal -

Gay removed himself from all competition ahead of last year's World Championships and has not competed since.

He also agreed to assist USADA in investigating the circumstances behind his positive test, providing assistance and all products he was using at the time he tested positive.

"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," USADA chief executive Travis T. Tygart said.

Providing assistance allowed Gay to receive up to a 75 percent reduction in the usual two-year ban under USADA regulations, setting the stage for the imposing of a one-year ban.

That suspension length is subject to appeal by the IAAF and the World Anti-Doping Agency (WADA).

"USA Track and Field is gravely disappointed any time an athlete uses performance-enhancing drugs and Tyson Gay's case serves as a lesson about the consequences of making poor decisions," USA Track and Field chief executive Max Siegel said in a statement.

"We appreciate that Tyson accepted responsibility and has assisted USADA by providing information to help battle the use of PEDs."

Gay's personal best of 9.69sec in 2009 at Shanghai makes him the joint-second fastest man ever behind Jamaican legend Usain Bolt, equal with Jamaican Yohan Blake.

In the 2007 world championships in Osaka, Gay won the triple of 100m, 200m and 4x100m relay, winning IAAF Athlete of the Year honors and becoming a gold medal favorite for the 2008 Beijing Olympics.

But Gay pulled a hamstring at the US Olympic trials and wound up making a semi-final exit in China.

Gay was second to Bolt in the 2009 worlds but in 2010 delivered Bolt's first defeat in two years and won the Diamond League 100m crown. But in 2011 he underwent right hip surgery and took a year to recover, barely reaching London, an effort now for nought in a career shadowed by doping disgrace.