UK Anti-Doping (UKAD) said it was "deeply concerned and shocked" by a Sunday Times report in which a British doctor alleged he had prescribed banned performance-enhancing drugs to 150 sportsmen including several Premier League footballers.
The paper said Dr Mark Bonar claimed his "clients" included an England cricketer, British Tour de France cyclists, a British boxing champion, tennis players and martial arts competitors as well as footballers.
In the past six years he had treated more than 150 sportsmen from the UK and abroad with banned substances such as erythropoietin (EPO), steroids and human growth hormone, and the performance improvements were "phenomenal", the report added.
Neither the newspaper nor Reuters was able to substantiate the claims made by the doctor.
UKAD chief executive Nicole Sapstead said the body had been aware of allegations against Dr Bonar after a sportsperson approached them two years ago but had not been able to act upon them because he was not affiliated to any particular sport.
"Under current legislation, UKAD has the power only to investigate athletes and entourage (including medics) who are themselves governed by a sport," she said.
UKAD had considered informing the General Medical Council, which overseas medical practitioners in Britain, but decided the evidence they had was insufficient for such a referral, Sapstead added.
UKAD chairman David Kenworthy said an independent review would be conducted into the issues raised by the report.
"They will be asked to look at the way the information supplied by the sportsperson was handled and whether proper procedures were followed," he said.
"They will also be asked to make any recommendations to improve the way in which intelligence is dealt with in the future so that UKAD can be as effective as possible in keeping sport clean."
The news is likely to cast a further shadow on the sporting world ahead of the Rio Olympics.
Russia was suspended from international track and field last year following a report exposing widespread cheating and corruption among its athletes.
The country faces a ban from the Olympics unless Russia can prove to the World Anti-Doping Agency and the IAAF governing body that it has met a series of conditions regarding its anti-doping operations.
Photograph: Alex Livesey/Getty Images
