"It is a unique event, there are people who break the rules in every profession," London Mayor Ken Livingstone said today. "I do not think that a small handful of riders that are breaking the rules diminishes those riders who finish the course."

An estimated 1 million fans turned out on July 7 for the Tour's 4.9-mile prologue in downtown London. Fabian Cancellara won the prologue, and Robbie McEwen won the 126-mile first stage from London to Canterbury.

Livingstone acknowledged it was unlikely that the Tour would start again in London before the city hosts the 2012 Olympics, but that a separate stage could be held in the British capital before then.

"We have made it clear that we want them to come back for the Grand Depart (big start) as soon as possible, but that is probably not for another six years," Livingstone said. "We have also been negotiating with them to see if we can get a stage coming through London before 2010."

Alberto Contador of Spain won this year's Tour after the ouster of leader Michael Rasmussen for allegedly lying to his Rabobank team about his whereabouts to evade doping controls.