Thomas Dekker is set to miss the Tour de France after the International Cycling Union began disciplinary proceedings after an anti-doping violation.

The 24-year-old Dutch rider, regarded as one of the peloton's most precocious talents after top-10 placings at Amstel Gold, Fleche Wallonne and Liege-Bastogne-Liege, is under suspicion following results of the biological passport programme which suggested an abnormal haematological profile and the detection of recombinant EPO - a blood booster - both of which would enable an athlete to carry more oxygen.

The UCI's suspicions were aroused by "blood samples collected from Mr Dekker in 2008 and 2009 (which) demonstrated convincing evidence of the use of the prohibited method of enhancement of oxygen transfer".

As a result a detailed review was carried out and a urine sample collected in December 2007 was found to contain recombinant EPO (Dynepo).

The news is a blow for Silence-Lotto team leader Cadel Evans, who has finished runner-up in the Tour, which begins on Saturday in Monaco, for the last two years.

A UCI statement read: "The International Cycling Union (UCI) today advised Mr Thomas Dekker that he has committed a potential violation under the UCI Anti-Doping Rules.

"Based on these rules, the UCI has instructed the Monegasque Cycling Federation, to which Mr Dekker is affiliated, to open disciplinary proceedings on this matter.

"The nature of Mr Dekker's haematological profile prompted the UCI to conduct a detailed review of the results of EPO analyses conducted on urine samples taken from him since the commencement of the biological passport programme.

"As part of this review, the UCI requested the WADA-accredited laboratory in Cologne to re-examine the results of a urine sample collected from Mr Dekker in December 2007.

"On 30 June 2009, the Cologne laboratory reported a finding of recombinant EPO (Dynepo) in this sample.

"This result was reported in accordance with new EPO detection and reporting rules approved by the World Anti-Doping Agency in May 2009.

"In accordance with the World Anti-Doping Code and the UCI Anti-Doping Rules, the UCI will make no further comment on this matter until a final decision has been made."