Tom Boonen has been barred from competing in the Tour de France after a positive out-of-competition test for cocaine.

The Belgian sprinter was suspended by his Quick Step team in May after testing positive for the drug for the second time in 12 months.

The 28-year-old first tested positive for the drug in May last year and was barred from competing in the Tour de France by race organisers the Amaury Sport Organisation (ASO).

He returned earlier this month in the Dauphine Libere and had hoped to rival Team Columbia-Highroad's Mark Cavendish for the points jersey at the Tour de France.

But the ASO have banned him from participating in a second successive edition of cycling's premier event.

A statement read: "Following Tom Boonen's recent test, after a first test in 2008, the Tour de France, after meeting Quick Step team representatives, can only state that the image and behaviour of Tom Boonen do not match the Tour de France's image or the one that should be promoted by such an exceptional champion.

"In these circumstances and in order to preserve his reputation, his image and those of the Tour de France, the ASO group has decided not to accept the presence of Tom Boonen in its event."

Boonen was not banned after his first test because cycling's governing body, the UCI, do not hand out penalties for use of the recreational drug unless it is during competition.

And they are taking the same stance with his second positive result.

A statement read: "The UCI management committee has decided not to institute disciplinary proceedings against Mr Tom Boonen for having allegedly taken cocaine out of competition, after the Belgian rider supplied a number of elements in his defence."