Six-time Olympic champion Usain Bolt has maintained his doping innocence after both Asafa Powell and Tyson Gay tested positive for a banned substance.

American Gay and Powell, Bolt's Jamaican team-mate, have previously clocked two of the four fastest 100m times in history but face bans of up to two years should their B samples return an identical result, after testing positive for oxilofrine earlier this year.

The recent scandal, which includes four other Jamaican athletes as well as Veronica Campbell-Brown, who was provisionally banned in June after testing positive for diuretics, has cast a shadow over the sport of athletics and raised questions over the integrity of Bolt, the 100m world record holder.

Bolt remains the only athlete inside the top five fastest men of all time to not have tested positive and the Jamaican insists he is clean.

"For me I don't say it's much of a surprise but there is a lot of details that are still to be discussed," Bolt told a press conference prior to the London Anniversary Games.

"There's a lot of things that haven't been said so I'm just waiting to see what happens. In life things happen and people make mistakes.

"In life you learn anything is possible, but as an athlete you have to be aware, but that's why you have a team to have to help you out with these things.

"I was made to inspire people and run and that's the gift I have. I know I am clean and I just want to improve the sport and that is what I am going to do.

"If you had been following me since 2002, you'd know I've been doing incredible things since the age of 15," the 26 year old added.

"I get tested all the time. Was tested day before yesterday. It's how it goes in the sport. I am clean, that's all I can say.

"I take vitamins, I don't take supplements. Have a team that checks to ensure nothing on the banned list.

"I hope to carry on putting on great performances on the track to get people talking about positive things about the sport."

Both Gay and Powell have blamed their respective positive tests on supplements being contaminated and the pair are set to miss next month's World Athletics Championships in Moscow.

"I have to trust my teammates," he added. "I have spoken to Powell through some BB[Blackberry Messenger] messages. He said things are rough at the moment.

"I told him to stay strong and stay focused and I hope everything will work out."