John Whittingdale has called for an urgent investigation into the British anti-doping watchdog after The Sunday Times reported the regulator received claims a doctor had prescribed banned performance-enhancing drugs to top sportsmen including several Premier League footballers.
The Culture, Media and Sport Secretary said he was "shocked and deeply concerned" by reports in The Sunday Times that the doctor, named by the newspaper as Dr Mark Bonar, had allegedly been secretly filmed discussing working with professional athletes who used banned treatments.
London-based Dr Bonar denied the allegations when they were put to him by the newspaper.
According to The Sunday Times, UK Anti-Doping (Ukad), the publicly-funded watchdog, was given "evidence" of the activities two years ago.
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. Once again, I am grateful to the excellent investigative journalism by The Sunday Times for bringing these apparent abuses to light.
"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."