By Duncan Mackay

Tyson Gay London 2012July 27 - Former world champion Tyson Gay is facing a suspension from athletics after the United States Anti-Doping Agency (USADA) confirmed that his B-sample had tested positive for banned performance-enhancing drugs.

Gay had already revealed that his A-sample had been positive from a May 16 out-of-competition test and USADA have confirmed analysis of the back-up sample was also positive, as was another "sample collected from the 2007 world 100 and 200 metres gold medallist.

"We can confirm that the B sample analysis of a sample collected from Mr Gay has been completed, and that the B sample analysis has confirmed the A sample findings," USADA chief executive officer Travis Tygart said in a statement.

"An additional sample collected from Mr Gay has also returned an adverse A sample finding.

"The results of these tests were expected given Mr Gay's acceptance of responsibility for the substances found in his body as soon as he was notified of the A sample results."

Gay had already withdrawn from the International Association of Athletics Federations (IAAF) World Championships in Moscow next month but could now face a ban of up to two years, depending on which substance he has tested positive for.

"We appreciate Mr Gay voluntarily removing himself from competition prior to the World Championships while we evaluate the circumstances surrounding his adverse analytical findings and work towards achieving a fair resolution of his case in accordance with the rules," Tygart said.

Tyson Gay Lausanne 2013Tyson Gay celebrates winning the 100 metres at the IAAF Diamond League event in Lausanne in a race where he beat Asafa Powell, who has also tested positive for drugs

Gay, a member of the US 4x100m relay team that won an Olympic silver medal at London 2012, blamed the result on having trusted someone who betrayed him, presumably regarding the acceptability of a substance that he ingested, but has so far given no further details.

Gay's website has not been updated since July 5, the day after he won the 100m at the IAAF Diamond League meeting in Lausanne in 9.79sec, the fastest time in the world this year.

He had won the race ahead of Jamaica's former world 100m record holder Asafa Powell, who revealed on the same day as Gay that he had also tested positive for a banned stimulant oxilofrine at his national championships and is also facing a ban from the sport.

The last occasion on which Gay's Facebook or Twitter accounts was updated was on July 8 when he posted a message of congratulations to Britain's Andy Murray winning the Wimbledon tennis title.

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