Former Tour de France champion Bjarne Riis, who confessed to doping to win the 1996 race, has criticised team sponsor Rabobank for allowing Michael Rasmussen to compete in this year's race.
Rasmussen was expelled from this year's Tour by his Dutch team while leading the race for allegedly lying about his whereabouts to evade drug testers.
But Riis believes that Rabobank is also culpable.
"It is Rabobank that has an explanation problem," Riis said.
"When they pick a rider for the Tour de France then it must be because they trust him. It is of no use to lose that confidence in the middle of the race.
"They should have left Michael to stay at home if (the warnings) were
Rasmussen missed random drug tests in May and June prior to the Tour.
The Danish rider said he had been in Mexico, but a former Italian cyclist claimed he saw him in Italy then.
Rasmussen took the Tour leader's yellow jersey after winning the eighth
stage on July 15.
He held it until after the 16th stage when he was kicked out four days before the three-week race ended on July 29.
Riis, who is now Team CSC manager and said in May he used EPO from 1993-98, couldn't be reached for further comment, but main sponsor CSC backed Riis, saying he launched the cycling team's rigorous anti-doping program.
Alberto Contador of Spain eventually won the 2007 Tour.