Athletics: Bolt - Athletics is cleaning up

Usain Bolt after victory in the men's 100m during the IAAF Diamond League Meeting Herculis. Photo / Getty Images

Usain Bolt has warned dopers they risk killing athletics and urged them to clean up their act for the sake of the sport.

The 30-year-old pleaded for clean sport ahead of his final individual 100 metres race at the World Championships this weekend.

Of the 30 best 100m times, 21 were achieved by athletes who have served drugs bans - with the other nine all coming from Bolt during a career which has earned eight Olympic gold medals and 11 world titles.

Athletics has been under a cloud, with the Russian federation banned for systemic doping since November 2015.

Several British athletes are also due to get medals which they lost out on because of dopers during the championships this month.

Jessica Ennis-Hill is to be awarded World Championships gold after Russia's Tatyana Chernova was stripped of her 2011 crown.

And Bolt, who holds the world records in the 100m and 200m, insisted dopers are endangering the future of athletics.

He said: "Hopefully athletes will see what's going on and understand that if they don't stop what they're doing the sport will die.

"Hopefully understand what the sport is going through and what they need to do as athletes to help the sport moves forward.

"Personally I think it was there (rock bottom). After the scandal on Russia I don't think it gets any worse than that. It's on its way back up now. No way but up you can go and forward.

"You can't be happy about doping at all, it's not good for the sport. But over the years we're doing a better job, it's getting clean and we're catching up to a lot of athletes.

"There's an understanding that, listen, if you cheat you will get caught. Over time the sport will get better.

"I said a couple of years ago it had to get really bad, when there's nowhere else to go but up.

"The only way track and field has left to go is up. We're going to go in the right direction and I'm happy about that situation."

Bolt was speaking in London for the final time ahead of Friday's 100m heats and Saturday's semi-final and final as he aims to defend his world title from Beijing.