Nine-time Olympic gold medallist Usain Bolt is unfazed by insinuations that he is guilty of drug use because he knows he is clean.

Bolt burst onto the scene by taking gold in the 100 metres at Beijing 2008 with a world record time of 9.69 seconds, prompting some to claim he did so by illegal measures.

The Jamaican has since trimmed that world record to 9.58secs and went on to complete an unprecedented 100m, 200m and 4x100m treble for the third successive games at Rio 2016, achievements he says will not be cheapened.

"I really don't let things like that bother me. It's because, over the years, you know that's going to happen. That's what they're going to ask," Bolt told The Guardian.

"I'm going to enjoy this, no matter. When you work so hard for what you have done, and it finally comes, it should feel good.

"I'm not going to let somebody else rob me of that moment. I feel good because I know I've done it clean."

Bolt overcame long-term rival Justin Gatlin to take gold in the 100m at Rio, the American getting booed as he lined up at the blocks for the final.

That reception came as a surprise to Bolt, though he struggled to feel sympathy following the mudslinging that has occurred between the two.

"I was really shocked. In all the years I've been doing track, I've never seen somebody get booed at a championship," said Bolt.

"[I felt sorry for him] a little bit. But then, after all the talking that was going on all season, not that much," he added with a chuckle.

Given Bolt's superiority in their head-to-head record, he would like to see Gatlin challenged whenever he claims to be capable of winning a race between the pair.

"The one thing that always annoys me is when Justin Gatlin always says: 'Oh, I'm going to beat Usain Bolt, blah, blah, blah.'," said the Jamaican.

"I'm like, why don't interviewers ask him, why should we believe you? I really want an interviewer, one day, to ask him that question – to say, 'You guys have got up 10 times, you've won one of them. Give me a good reason why we should write that Gatlin's going to beat Usain Bolt?'

"People should call you out on it. But if you are actually the best, then I feel as long as you don’t overdo it, it's fine."