Doping findings rough for athletics: Bolt

Olympic sprint champion Usain Bolt said the finding of 31 positive doping samples from the 2008 Beijing Olympics marked a rough point for athletics, but backed the World Anti-Doping Agency in its effort to crackdown on drug use in the sport.

Thirty-one athletes from six sports could be banned from this year's Rio Olympics after failing dope tests when 454 samples were reexamined from the 2008 Games, the International Olympic Committee said on Tuesday.

"It's rough in the sport," the six-times Olympic Champion told British media. "Something that's been tarnishing the sport for years."

The IOC said it would begin re-testing athletes likely to take part in the Rio Games to prevent any drug cheats from competing.

"Hopefully, we can take steps forward in making the sports better and in the coming years we won't have these problems," said Bolt, 29.

"But I think it's a process, and I think over time we will get better because they're (WADA) doing such a good job."

Bolt will take part in the 100m at the Golden Spike IAAF World Challenge in Ostrava in the Czech Republic on Friday.