Usain Bolt says he has lost all respect for Carl Lewis after the United States sprint legend restated his concerns over the toughness of Jamaica's drug-testing policy.

Speaking after winning the 200 metres at the London Olympics to seal a remarkable second consecutive sprint double, Bolt said he held sprint icon Jesse Owens in high regard, but that Lewis was merely attention-seeking.

"For me, Jesse Owens I have a lot of respect for. He's a great athlete," Bolt said of the four-time gold medallist.

"[But] I'm going to say something controversial right now.

"Carl Lewis - I've no respect for him.

"The things he says about the track athletes is really downgrading for another athlete to be saying something like that about other athletes.

"I think he's just looking for attention really because nobody really talks about him, so he's just looking at attention."

Lewis won nine gold medals between 1984 and 1996. Bolt has five with a prospect of a sixth in the men's 4x100m relay.

Lewis has consistently questioned the performances of Jamaica's sprinters, refusing to join in the universal applause for Bolt after he raced to his first Olympic double in 2008.

"No-one is accusing anyone," Lewis said in an interview shortly after Beijing.

"But don't live by a different rule and expect the same kind of respect ... I'm not saying they've done anything for certain. I don't know.

"But how dare anybody feel that there shouldn't be scrutiny, especially in our sport?

"The reality is that if I were running now, and had the performances I had in my past, I would expect (doping critics) to say something.

"I wouldn't even be offended at the question. So when people ask me about Bolt, I say he could be the greatest athlete of all-time.

"But for someone to run 10.03 one year and 9.69 the next, if you don't question that in a sport that has the reputation it has right now, you're a fool. Period."

Bolt emphasised that Jamaica's incredible sprint success is all down to hard work.

"That was really sad for me when I heard the other day what he (Lewis) was saying, so for me it was upsetting," Bolt said.

"So for me I've lost all respect for him, all respect."

Usain Bolt poses with his gold medal on the podium after doing the double again. ( Reuters: Eddie Keogh )

Who's the greatest?

Bolt also said that despite his impressive record, decathlete gold medallist Ashton Eaton deserved to have the tag of "best athlete in the world".

Bolt declared himself the "greatest athlete to live" after successfully defending his 200m title in 19.32 seconds.

On the same day Eaton, the world record-holder from the US, wrapped up the decathlon, the gruelling 10-discipline event spread over two days.

And when questioned directly, Bolt backed down from his declaration.

"I'm a great athlete, but to do 10 events, especially the 1500m, I have got to give it to him," he said.

Decathlon silver medallist Trey Hardee had earlier, and rather more pointedly, insisted that the accolade of world's best athlete belonged to his US team-mate Eaton.

"So Ashton doesn't have to sound selfish or self-centred, Ashton is the best athlete that has ever walked the planet, hands down," Hardee said, interrupting a question to Eaton.

"The title bestowed upon the Olympic champion in decathlon is the world's greatest athlete and Ashton's the world record holder in that event, the same reason Usain Bolt can be the fastest man on the planet because that's the title that's bestowed upon those event winners.

"Just because you're fast doesn't make you an athlete.

"Ashton was the world's fastest decathlete for a number of years but he became a real decathlete and that's what you've seen this year."