World cycling chief Pat McQuaid insisted the sport had moved on from its murky past as the body comes under pressure to respond to doping evidence against Tour de France icon Lance Armstrong.

McQuaid admitted cycling had suffered "big damage" from the affair but he said better tests meant riders were now much cleaner than previous days, which are in focus since claims targeting Armstrong were released this week.

"The sport has moved on," the International Cycling Union (UCI) president told AFP at the Tour of Beijing. "The peloton today is completely different."

"There is big damage to the image of the sport, but the sport is going very well," he added.

Armstrong, who denies taking banned substances, is accused by the US Anti-Doping Agency (USADA) of being at the heart of "the most sophisticated, professionalised and successful doping program" ever seen in sport.

The UCI is yet to respond to USADA's 1,000-page document, which raises questions about how Armstrong apparently managed to evade detection, and contains a claim that he paid a bribe to hush up a positive test.

The body is also yet to endorse or reject USADA's move to ban Armstrong from cycling for life and strip him of his Tour titles, a sanction that currently only has force in the United States.

"The UCI has received the dossier two days ago, 1,000 pages, and so our lawyers are studying that at the moment and we have 21 days to come up with a response," McQuaid said earlier this week.

He added: "It would be wrong of me to second guess or pre-empt what our lawyers might decide, so I'd wait until then. The UCI will wait until that work has been done and then the UCI will make a statement."

The scandal widened further on Saturday when former Australian Olympian Matt White confessed to being part of an Armstrong doping conspiracy and quit his roles with pro cycling team Orica-GreenEDGE and Cycling Australia.

"I am sad to say that I was part of a team where doping formed part of the team's strategy and I too was involved in that strategy," White said in a statement.

"My involvement is something I am not proud of and I sincerely apologise to my fans, media, family and friends who trusted me and also to other athletes in my era that consciously chose not to dope."

Less than 24 hours earlier Johan Bruyneel, the Belgian who managed Armstrong during his Tour de France victories, parted ways with the Radioshack team in light of "a number of testimonies as a result of their (USADA's) investigation".

"Johan Bruyneel can no longer direct the team in an efficient and comfortable way," a team statement said. "His departure is desirable to ensure the serenity and cohesiveness within the team."

The Armstrong accusations are by far the most damaging in a sport that is regularly rocked by doping revelations. But some riders were defiant when approached by AFP in Beijing, claiming they belonged to a different era.

Italian rider Davide Cimolai, who races with Lampre-ISD, said he and others were not surprised by the Armstrong report but felt it should have come out sooner. "He's guilty and he should have been punished, but not now," he said.

He said the news had had a "negative impact" on the sport but that "if you look at other sports, they have much less controls than cycling".

Austrian rider Marco Haller, who won stage four of the Beijing event on Friday, said the allegations were in the past and did not concern him.

"I really don't follow it, I don't read articles on the internet, nothing," the Katusha Team rider said.

"I came up in the professional level this year and I managed to win a stage here and I know I did it clean. So it doesn't matter what other people (do). What happened 10 years ago, it's not my problem."

AFP