American sprinter Tyson Gay's B sample has returned a positive result for banned substances.
Gay tested positive for performance-enhancing drugs earlier this month and has since pulled out of July's World Championships in Moscow.
The US Anti-Doping Agency's chief executive Travis Tygart confirmed that Gay's 'B' sample also tested positive.
"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," Tygart said.
"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."
Jamaican sprinters Asafa Powell and Sherone Simpson also tested positive for banned stimulants earlier this month.
