Uefa denies drug taking in football at "significant level"
Uefa has denied claims that drug taking among top players is at a "significant level" and said results from a study it carried out needed clarification.
The Sunday Times reported that the study showed high testosterone levels were found in urine samples of 7.7% of 879 players who were tested.
The paper said this "indicated" a possible use of anabolic steroids.
"This study doesn't present evidence of potential doping," said European football's governing body.
Uefa said "the lack of standardisation" in the testing procedures and the "inability" to carry out testing on a B sample, as required by World Anti-Doping Agency's code, meant no "scientific evidence" could be produced.
It added that the introduction of a biological passport in football would be beneficial by offering further analysis in the case of atypical test results.
The samples came from players who played in the Champions League and Europa League and were tested between 2008 and 2013 by scientists from 12 anti-doping laboratories.
None of the 68 players who allegedly had "atypical" drug test results face sanctions as the samples were provided anonymously.
The Sunday Times reported that they and German broadcaster ARD/WDR passed the study to professor Julien Baker, who had been researching steroid use for 20 years.
Baker is quoted as saying: "If the findings are accurate then this sheds light on previously untold levels of suspected cheating in Europe's top competitions."
The Uefa statement added: "Uefa has now implemented a new steroid profiling programme which has come into operation at the start of the 2015-16 season.
"The programme will boost the already strong deterrent effect of Uefa's testing programme, as it will help better detect the effects of doping over time, thereby complementing existing direct anti-doping testing."