John Whittingdale has called for an urgent investigation into the British anti-doping watchdog's response to allegations a doctor had prescribed banned performance-enhancing drugs to a sportsman.
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 been secretly filmed allegedly discussing working with numerous professional athletes who used banned treatments.
London-based Dr Bonar denied the allegations when they were put to him by the newspaper and said he had not breached rules laid out by the General Medical Council (GMC).
According to The Sunday Times, UK Anti-Doping (UKAD), the publicly-funded watchdog, was given "evidence" of the activities two years ago but failed to take action.
UKAD officials confirmed they received information from the sportsman, however the body said the doctor fell outside their jurisdiction and they did not believe there were grounds to refer the case to the GMC.
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 gain, 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."
UKAD chief executive, Nicole Sapstead said the watchdog was "deeply concerned and shocked" by the allegations made in The Sunday Times.
She acknowledged that UKAD had received allegations involving Dr Bonar in April and May 2014 during interviews with the sportsman, who has not been named.
"Following those interviews and an investigation, UKAD found that there was nothing to indicate that Dr Bonar was governed by a sport and UKAD had no other intelligence to corroborate the sportsman's allegations," Ms Sapstead said.
UKAD recommended the sportsman gather more information and pass it on to the GMC, the doctors' regulator, "if appropriate".
In October 2014 the sportsman supplied UKAD with "handwritten prescriptions" that he said had been issued by Dr Bonar.
The notes were given to an independent medical expert for analysis.
"After assessing all the evidence, as per the National Intelligence Model, UKAD did not believe that there were grounds, at that point, to refer the case to the GMC," Ms Sapstead said.
UKAD chairman David Kenworthy said an independent review of the allegations against it 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.
"UKAD is a publicly funded body and it is correct that it be held to account for any actions it takes. That accountability rests with the independent board," he said.
The watchdog said it would not comment any further on the issue.
The Press Association is attempting to contact Dr Bonar for comment.