There's no evidence that Lance Armstrong used a performance-enhancing drug during the 1999 Tour de France cycling race, an independent investigation concluded Wednesday.
In his 132-page report, a Dutch investigator also said French anti-doping authorities may have acted improperly in dealing with allegations against the seven-time Tour de France champion.
The investigation was spurred by a report published last August in the French sports daily L'Equipe.
Lance Armstrong captured a record seven consecutive Tour de France titles.
It alleged that six of Armstrong's urine samples from the 1999 Tour, the first in his record seven-straight Tour titles, returned positive for the endurance-boosting hormone EPO after a retest in 2004.
Armstrong has repeatedly denied ever using banned performance-enhancing substances.
In October, the International Cycling Union (UCI) appointed Dutch lawyer Emile Vrijman to investigate the handling of the urine tests at France's national anti-doping laboratory.
Vrijman said his report "exonerates Lance Armstrong completely with respect to alleged use of doping in the 1999 Tour de France."
Wednesday's report said the French national anti-doping lab and the World Anti-Doping Agency may have "behaved in ways that are completely inconsistent with the rules and regulations of international anti-doping control testing."
The report recommended organizing a tribunal to discuss possible legal and ethical violations by the anti-doping authorities, and to decide if sanctions were necessary.
The French anti-doping lab has been accused of violating confidentiality regulations.
Vrijman also said further investigation was needed concerning the leaking of the test results to L'Equipe.
In February, the UCI revealed its chief medical officer Mario Zorzoli provided the French newspaper with the doping control documents.
Zorzoli was slapped with a one-month suspension by cycling's world governing body earlier this year, but has since been reinstated.
Vrijman's report also ruled the UCI had not damaged Armstrong by releasing doping control forms to L'Equipe.
The American cycling star retired last July after winning his seventh consecutive Tour de France championship.
With files from the Associated Press