Impey tests positive
South African rider Daryl Impey has been withdrawn from racing by Orica-GreenEdge after testing positive for the banned substance Probenecid.
Impey returned positive A and B samples at the South African national championships in February.
The 29-year-old broke the news on his website and denied any wrongdoing.
He said: "I had no knowledge of Probenecid, nor have I ever taken the substance knowingly in any manner. I am committed to drug-free sport and fully intend to take all steps necessary to clear myself of any suspicion.
"The notification came as a complete shock to me. I am extremely distressed by the finding, as I have always raced clean throughout my career. Every result that I have achieved to date has been as a result of hard work and dedication on my part.\"
Impey made headlines at last year's Tour de France by becoming the first African rider to wear the yellow jersey, which he held for two days.
He became South African time trial champion for the third time at February's national championships and also finished second in the road race.
Probenecid is a diuretic drug that is commonly used to treat arthritis.
Orica-GreenEdge said in a statement: \"The team would like to underline that it respects Daryl Impey's right to prove his full innocence and will not comment any further until the process has run its due course and final conclusion has been made.
"As per the team's code of conduct, Daryl Impey will not feature on the team's roster until the case has been closed and he is fully eligible to ride.\"