The Culture Secretary has ordered an inquiry into claims that a British doctor prescribed banned performance-enhancing drugs to 150 "elite" sports stars.
John Whittingdale said he was "shocked and deeply concerned" by the allegations reported in The Sunday Times (£).
The newspaper said that Dr Mark Bonar was secretly filmed describing prescribing the drugs to sports stars including Premier League footballers.
It was also claimed that the UK Anti-Doping Agency (Ukad), the publicly-funded watchdog, was given "evidence" of the activities two years ago.
Dr Bonar is reported to have claimed to have prescribed drugs such as erythropoietin (EPO), steroids and human growth hormone, to the sports professionals, which are said to include:
Several Premier League football players
An England cricketer
The Sunday Times said there is no independent evidence that Dr Bonar treated Premier League players. It added that there is also no evidence that any clubs were aware of any wrongdoing.
The newspaper also said they had contacted athletes from several different sports who had been named by the doctor, who either denied Bonar had treated them or declined to comment.
Dr Bonar has denied doping sports stars to enhance their performance and told the newspaper he had not breached rules laid out by the General Medical Council (GMC).
The fact that some of my patients happen to be professional athletes is irrelevant. If they have proven deficiencies on blood work and are symptomatic, I will treat them.
Ukad chief executive, Nicole Sapstead said the watchdog was "deeply concerned and shocked" by the allegations made in The Sunday Times.
In a statement, the body confirmed that it did begin an investigation into Dr Bonar after receiving information from an unnamed sportsman.
But the agency found that he fell outside their jurisdiction and they did not believe there were grounds to refer the case to the GMC.
Chairman David Kenworthy said an independent review of the allegations against the Ukad would be conducted "as soon as possible", to examine the information passed to them in 2014 and to discern if the proper procedures were followed.
Mr Whittingdale said: "Sports fans are entitled to be sure that what they are watching is true and fair with all athletes competing on a level playing field."
I have asked for there to be an urgent independent investigation into what action was taken when these allegations were first received and what more needs to be done to ensure that British sport remains clean. There is no room for complacency in the fight against doping and the government is already looking at whether existing legislation in this area goes far enough. If it becomes clear that stronger criminal sanctions are needed then we will not hesitate to act.
Commenting on the doping allegations, Niall Dickson, chief executive of the GMC, said: "These are serious allegations and we will follow them up as a matter of urgency."
Arsenal, Chelsea and Leicester City said they were"disappointed" by the claims and stressed their teams followed strict anti-doping protocols.