A doctor has described allegations he prescribed performance-enhancing drugs to sports stars as "false and very misleading".
A Sunday Times report alleged Dr Mark Bonar claimed to have treated more than 150 sportsmen and women - including Premier League footballers, British Tour de France cyclists, tennis players and a British boxer - with banned substances including EPO, human growth hormone and steroids.
A Twitter account purporting to belong to Bonar on Sunday night, although not verified, read: "The @SundayTimesNews allegations are false and very misleading. I have never had a relationship with any premier football club or player.
"I have never prescribed Androgen therapy for the purpose of performance enhancement.. I treat symptomatic men with low Test levels."
Androgen therapy is a class of replacement therapy of hormones, such as testosterone, which could have performance-enhancing benefits.
An independent inquiry into the allegations is expected to formally begin on Monday or Tuesday.
Culture, Media and Sport Secretary John Whittingdale demanded an urgent investigation into UK Anti-Doping's (UKAD) response after the newspaper claimed the organisation was given information about the doctor's alleged doping activities - which he denies - two years ago but failed to take action to stop him.
UKAD is in discussions with officials from Whittingdale's department over who should lead the inquiry and what its remit will be.
Whittingdale, who says he will meet UKAD officials on Monday, has pledged to strengthen the law if investigations throw up any loopholes.
It is understood although UKAD was made aware of general allegations made against Dr Bonar by an unnamed sportsman in April and May of 2014 the information was vague and not at the level of detail reportedly uncovered by The Sunday Times.
UKAD was subsequently supplied with handwritten prescriptions apparently issued by Bonar which were given to an independent medical expert for analysis.
"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," UKAD chief executive Nicole Sapstead said.
"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 General Medical Council (GMC)."
UKAD recommended the sportsman who brought the allegations to its attention gather more information and pass it on to the GMC - the national body responsible for the registration and conduct of doctors - "if appropriate" as the doctor was outside its jurisdiction.
The GMC has confirmed while Bonar is registered with it, he does not have a current licence to practise medicine in the UK.
The Omniya Clinic in London, where the doctor rented private consulting rooms to treat his patients, said it ended his professional services agreement on Friday after learning he does not hold a current licence.
The Press Association is attempting to contact Bonar for comment.
Leicester, Arsenal and Chelsea, the three Premier League clubs named in the report, have all expressed their disappointment at the publication of doping allegations made against them which they claim are "without foundation".
The Sunday Times report also claimed Rob Brinded, a former Chelsea fitness coach, had "collaborated" with Bonar.
Brinded admitted meeting Bonar, but distanced himself from the doctor and the allegations in a statement issued through his solicitors.
"I do not and have not ever worked or collaborated with Dr Bonar," Brinded said.
"I have never referred any athletes to him and, to the best of my knowledge, none of my clients, athletes or otherwise take performance enhancing drugs."
A spokesman for British Cycling called for The Sunday Times to disclose all the evidence it had uncovered.
The Football Association welcomed UKAD's independent review, as did the World Anti-Doping Agency.
WADA wrote on Twitter: "WADA wholeheartedly supports independent review of @thesundaytimes allegations in the UK. We await conclusions from inquiry with interest."
WADA wholeheartedly supports independent review of @thesundaytimes allegations in the UK. We await conclusions from inquiry with interest— WADA (@wada_ama) April 3, 2016