Millar would have tested negative for EPO many times

The performance director of British Cycling told BBC Sport that Millar's confession had come as a big surprise.

But he called parts of the professional cycling world "a dangerous environment" for a man to ply his trade.

"We have to co-ordinate our efforts and keep up the fight against doping and have zero tolerance," Brailsford said.

"I am greatly saddened by the episode and to lose somebody of David's calibre to the British Olympic team is a blow.

"But I think from a wider perspective cycling doesn't need this type of story and it's a blow to the sport.

It knocks back one opportunity for one medal, but Britain has lots of other chances - here's not a domino effect here Dave Brailsford

"If we'd have known anything about this, we'd have done something straight away - we have a zero tolerance policy."

Brailsford said there was a "cultural problem" in cycling.

And expressed fears that many pro riders were going undetected despite using drugs.

"Millar's admitted now to taking EPO and yet he'll have been tested many times before without testing positive.

"So one must assume that there are ways and means of getting around the testing system as it currently exists."

Millar out of Olympics

But Brailsford was quick to assert that the British cycling programme was clean and that the Olympic team would not fall apart in Millar's absence.

"We'd have been expecting him to win a gold medal, but we won't lose focus and we still have very high expectations going into the Olympic Games.

"It knocks back one opportunity for one medal, but we have lots of other chances. There's not a domino effect here.